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🔍 Read the full analysis: How Three AI Tools Support My September 2026 Work on ThorstenMeyerAI.com

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TL;DR

Thorsten Meyer’s September 29 assessment assigns Opus 5.5 to building, GPT-6.1 Sol to detailed review, and a decision model called Jev to high-volume routing. The comparisons cite Artificial Analysis Intelligence Index v4.3.x and estimated task costs; Meyer says teams should test models against their own work before switching.

Thorsten Meyer said on September 29 that he uses Claude Opus 5.5 as his main model for building, GPT-6.1 Sol for detailed work and review, and a decision model called Jev for high-volume routing judgments. His account compares benchmark scores with estimated cost per task, arguing that model choice now depends on whether a system clears a team’s quality bar at an acceptable cost.

Meyer bases most of his score comparisons on the Artificial Analysis Intelligence Index v4.3.x, which he describes as a measure of general capability rather than a verdict on any particular workload. In his table, Opus 5.5 scores 58 at its top setting and costs an estimated $5.98 per task. GPT-6.1 Sol scores 51 at xhigh and costs $0.39 per task. These figures are index results and task-cost estimates reported by Meyer, not guarantees for other users or tasks.

His stated workflow gives Opus 5.5 the main development role: high for features, APIs and refactors, and xhigh for harder work such as architecture and migrations. He uses GPT-6.1 Sol at high or xhigh to examine a specific file or change and to review Opus’s work. He says a review model from a different family can provide a useful second perspective, and that Sol’s estimated cost makes it practical to run on meaningful changes.

Meyer assigns narrower tasks to other systems: Sonnet 5.5 at high for scoped subtasks and documents, Luna for classification and extraction, and Astra or Fable as second opinions when Sol and Opus disagree. Jev, which he describes as unable to write sentences, handles yes-or-no and routing decisions at high volume. The source does not provide benchmark or cost figures for Jev.

At a glance
reportWhen: Published September 29, 2026; GPT-6.1 S…
The developmentThorsten Meyer published a September 29 account of how he assigns three AI tools to building, review and routing work, using benchmark scores and task-cost estimates.

Opus builds. Sol reviews. Jev decides.

The September 2026 AI stack in one page: six frontier models on one price curve, and a decision model for the high-volume judgements that do not need a sentence.
Scores: Artificial Analysis Intelligence Index v4.3.x. Data as of 29 September 2026.
BuildsClaude Opus 5.5 at high or xhigh effort
Digs and reviewsGPT-6.1 Sol at high or xhigh effort
DecidesJev on high-volume yes/no and routing calls

One price tape, six models

Put every model on the same cost-per-task ruler and capability looks compressed. The bill does not.
Price tape: cost per task of six models on a log scale, from GPT-6 Luna at $0.07 to Fable 5.1 at $7.63$0.05$0.10$0.50$1$5$10cost per task, log scale: each tick is a different order of magnitudeGPT-6 Lunaindex 37 · $0.07GPT-6.1 Solindex 51 · $0.39 (xhigh)GPT-6 Astraindex 53 · $3.26Opus 5.5index 58 · $5.98Sonnet 5.5 · index 56 · $7.60Fable 5.1 · index 53 · $7.63about 100× from the cheapest to the priciest, but only 21 index points between them

Score against cost, at every effort setting

Each dot is an effort level. Opus 5.5 at high already matches Astra and Fable at max on this index, for less money.
Intelligence Index score against cost per task for each effort setting of six models$0.01$0.10$1$102030405060cost per Intelligence Index task, log scaleindexOpus high / xhigh: my defaultOpus 5.5Sonnet 5.5Fable 5.1GPT-6 AstraGPT-6.1 Sol (new)GPT-6 Sol (Sep 22), dashedGPT-6 Lunaup and to the left is better
Astra and Fable are shown at their top published setting. Luna starts at $0.0045 per task. GPT-6.1 Sol has no low or max setting published yet.

The effort dial moves the bill more than the model

Going from medium to max on Opus costs 4.46× more for 7 points. That is why I run high or xhigh.

Claude Opus 5.5

$0.55
42
$1.34
51
$1.82
54
$3.46
56
$5.98
58
low
medium
high
xhigh
max
Solid bars are where I run it. Max adds 2 points over xhigh for 73% more cost.

Claude Sonnet 5.5

$0.41
36
$0.59
41
$1.08
47
$2.74
52
$7.60
56
low
medium
high
xhigh
max
Best value is high. At max it writes about 193k output tokens per task, the most measured.

GPT-6.1 Sol: near-Astra scores at a fraction of the price

Launched 29 September at $2 in and $10 out per 1M tokens. It sits 1 to 2 points under Astra and Fable, and Opus xhigh still leads it by 5.

Three published settings

SettingIndexCost per taskOutput tokensFirst token
medium48$0.2115M5.3 s
high50$0.3225M57 s
xhigh51$0.3936M69 s
Median for comparable models is 82M output tokens. High and xhigh are not interactive: plan for a wait before the first token.

Same score band, very different bill

GPT-6.1 Sol xhigh
$0.39index 51
Opus 5.5 high
$1.82index 54
GPT-6 Astra max
$3.26index 53
Opus 5.5 xhigh
$3.46index 56
Fable 5.1 max
$7.63index 53
Cost per Intelligence Index task. A one-point gap is inside the noise.

My stack: who builds, who reviews

Opus does the work. A second model family reviews it, because a different reviewer catches what the author cannot see.
Stack diagram: Opus 5.5 builds at high effort, escalates to xhigh, and sends every change to GPT-6.1 Sol for review; Astra or Fable give a second opinionOpus 5.5 · xhighhard problems: architecture,migrations, trust boundariesOpus 5.5 · highMAIN BUILDERfeatures, APIs, multi-filework, refactorsescalate when it gets hardGPT-6.1 Solhigh or xhighdigs into details andreviews every change$0.32–0.39 per taskdifffindingsAstra or Fablesecond opinion, 8 to 20×the cost per taskif they disagreeSonnet 5.5 · Lunaside work: scopedsubtasks, bulk checksand routingFailed review? Hand Opus the failing case and the evidence.Never just “try harder”: effort cannot supply a missing requirement.
Effort is not capability. Turning the dial up does not make a model smarter.
Effort cannot fill gaps. A missing requirement stays missing at any setting.
Different model, same spec. That is not independent review if both read the same flawed brief.
Green tests are not approval. Passing tests only prove what the tests cover.

Cheaper tokens are not cheaper work

Illustrative, not measured: $1 of model time plus 4 minutes of review at $45 an hour. Halving the model price saves 12.5% of the total. One extra minute of review erases it.
$4.00
review $3.00
model $1.00
Baseline
$3.50
review $3.00
model $0.50
Model price cut 50%
$4.25
review $3.75
model $0.50
Cheaper model plus 1 extra minute of review
Track cost per accepted result: model, tools, review and rework, divided by the results someone actually uses.

Read the numbers with four warnings

The index movesFable scored 66 on an earlier version and 53 on v4.3. Compare within one version only.
Fallback is includedFlagged cyber and biology tasks route to older Anthropic models, now on Sonnet 5.5 too.
Max is not productionReal deployments run medium or high, where gaps narrow and costs fall.
Your work decidesShadow-test on your own tasks. Budget cost per task, not per token.

Part 2: Jev, the model that decides instead of writing

Jev cannot write, summarise or extract. It answers narrow typed questions with a probability and an honest confidence, in under a second, for about $0.04 per million input tokens.

One call in, typed answers out

Your code, not Jev, decides what to do with each answer, usually by confidence band.
Jev flow: state and typed questions go into one Jev call; typed answers with confidence come out; code acts alone, escalates the gray zone, or logsStatea ticket, a story,a site profile,a log line …+ typed questions,many per callJevone call0.3 to 0.9 s$0.042 / M tokens inAnswersnoul: 0.03choice: billing p 0.91, conf 0.86score: 2.7 of 3 conf 0.64code branches on thisAct aloneconf ≥ 0.8Escalategray zone toLLM or humanLogmeasure first

Three question types

noul
A yes/no question. Returns the probability of yes, 0 to 1.
gates, flags, filters
choice
Pick one option. Returns the choice, a probability per option, and a confidence.
routing, classification, taxonomy
score
Rate on your ordered levels. Returns a position (it can fall between levels) plus a confidence.
quality, fit, severity, priority

Confidence is the superpower

In my own measurement on a 31-topic classification, Jev agreed with a frontier LLM almost every time it was sure, and rarely when it was not. So: decide the clear cases, route the gray zone.
confidence 0.8 or higher
97–99%
all answers
89%
confidence below 0.5
42%
Agreement with a frontier LLM, my production data, September 2026, rounded.

Three uses running in my publishing operation

About 90,000 decisions so far. Checks I could only afford on a sample now cover everything.
$2.01
Language check
78,889 articles scanned overnight. 1,576 in the wrong language found, 1,553 fixed in place.
22%
Relevance gate
About 10,000 story-to-site pairings judged in 3 days. Only 22% were clearly on-topic.
89%
Classifier fallback
Agreement with the primary LLM across 31 topics, used when that LLM errors.

The fit test, then the shadow test

Use Jev only when all four hold. Then prove it on past decisions before it acts on anything.
High volumeThousands of small calls, not a handful of big ones.
Narrow questionNo multi-step reasoning needed.
Cheap errorsOr unsure cases go to something smarter.
Heuristic failsVisibly, and measured, not assumed.
  1. Replay 300 to 500 past decisions
  2. Compare overall and per confidence band
  3. Read 20 disagreements, decide who was right
  4. High band at 95% or better?
  5. Own flag, off by default
  6. Canary on 5 to 10 units
  7. Roll out in the confident band only

24 use cases, sorted by how well they fit

Start from the strong fits. The amber ones need a measurement before you trust them, and the red ones fail one of the four conditions.
in productionstrong fitmeasure firstpoor fit

Proven in production

  • 1Relevance gate
  • 2Language check
  • 3Classifier fallback

Publishing and content

  • 4Thin-source detector
  • 5Same-event dedupe
  • 6Product fits roundup
  • 7Disclosure present
  • 8Headline quality
  • 9Comment moderation

Commerce and support

  • 10Support-ticket routing
  • 11Return-reason coding
  • 12Review to feature complaints
  • 13Catalogue taxonomy
  • 14Order-fraud pre-triage

Software and AI systems

  • 15LLM guardrail
  • 16RAG passage filter
  • 17Citation check
  • 18Tool and intent routing
  • 19Log-line triage
  • 20PR risk triage

Business ops and home

  • 21Inbox triage
  • 22Expense categorisation
  • 23Lead qualification
  • 24Smart-home intent

Limits, cost and one hard rule

No writing, summarising or extractionPair it with an LLM for the write step.
No world knowledgePut a snippet in the state; a bare name means nothing.
Reads your wording literallyA rewording moved my results about 2 points. Freeze it, re-measure after changes.
Weaker on non-English, maths, datesKeep those checks on an LLM. Early access, hosted API only.
100,000 decisions ≈ $2.50
About 60M input tokens at $0.042 per million, output free, roughly 600 tokens per three-question call. Latency 0.3 to 0.9 seconds.
Never the sole decision-maker for consequences about people. Hiring, credit, medical and legal outcomes stay with a human. Jev can sort and flag. A person decides.
Sources. Model scores, cost per task and speeds: Artificial Analysis, Intelligence Index v4.3.x, including the GPT-6.1 Sol medium, high and xhigh pages, checked 29 September 2026. Astra and Fable scores from the Artificial Analysis v4.3 announcement. Jev figures are my own production measurements, September 2026, rounded. The review-bill example is illustrative. Read the full article on thorstenmeyerai.com.

How Cost Shapes Model Roles

The account illustrates a practical purchasing question for teams using AI in software and knowledge work: how much capability does a task require, and what does that level cost? Meyer’s figures put Sol xhigh at $0.39 per task, compared with $3.26 for GPT-6 Astra and $7.63 for Claude Fable 5.1, while their listed index scores are relatively close. If those estimates hold for a team’s own tasks, using a lower-cost model for routine review could make more frequent checks affordable.

Cost also changes with the effort setting. Meyer reports that Opus 5.5 rises from $1.82 per task at high to $3.46 at xhigh and $5.98 at max. He says the maximum setting adds two index points over xhigh for 73% more estimated cost. These comparisons suggest that settings deserve attention alongside model selection, but benchmark scores alone do not establish whether added expense improves outcomes in a specific workflow.

Meyer cautions that cheaper model use does not automatically mean cheaper work: additional human review can outweigh token savings. His recommendations are based on his own workflow and the cited index, so readers would need to measure quality, time and costs on their own tasks before adopting the same split.

The September Model Comparisons

Meyer frames his account around a shift in the AI market: several models have scores within roughly 20 index points, while their estimated cost per task varies widely. The source lists Opus 5.5, released September 22, with a top-setting score of 58; Sonnet 5.5, released September 28, at 56; and GPT-6.1 Sol, released September 29, at 51 for xhigh. It lists Fable 5.1 at 53, GPT-6 Astra at 53, and GPT-6 Luna at 37.

The reported comparisons have limits. Artificial Analysis’s index is a general-capability benchmark, and the source does not show how its tasks map to Meyer’s actual development and review work. Meyer says one index point may fall within measurement noise and recommends shadow-testing before changing a workflow. His article also distinguishes benchmark results from its estimated costs per task, which may depend on how a task is defined and run.

“Which model clears my quality bar at the lowest cost per task?”

— Thorsten Meyer

Limits of the Cost Estimates

The source does not provide enough detail to independently assess how its cost-per-task estimates were calculated or how closely the index tasks match Meyer’s workload. It also does not report a controlled comparison of the proposed workflow against alternatives, or measured changes in software quality, review time or total cost.

Meyer notes that GPT-6.1 Sol’s low and max settings were not yet listed in the index and says a one-point score difference may be within noise. The source’s final cost example is cut off after saying that halving model price saves 12.5% of real cost and that an extra minute of human review erases that saving; it labels the example illustrative, not measured. The full assumptions behind that calculation are therefore unclear.

The article gives no benchmark scores or task-cost estimates for Jev, and does not explain how the model handles errors in routing decisions. It remains unclear whether the recommended assignments would produce similar results for other teams, prompts or software tasks.

Test Before Changing Workflows

Meyer recommends shadow-testing models on a team’s own tasks before switching systems. That would let teams compare quality and cost on the work they actually need done, including whether a lower-cost review pass catches issues that matter and whether extra human checks erase the savings.

Further comparisons may change as index coverage expands. The source says low and max results for GPT-6.1 Sol were not yet available at publication. It does not give a date for those results or announce a formal next test, so the timing of additional evidence remains unknown.

Key Questions

Which models does Meyer use for building and review?

Meyer says he uses Opus 5.5 for building and GPT-6.1 Sol at high or xhigh for detailed analysis and review.

How much does GPT-6.1 Sol cost per task in the cited comparison?

The source lists estimated costs of $0.21 at medium, $0.32 at high and $0.39 at xhigh. These are the article’s figures based on the cited index, not a universal price for every task.

What does Meyer use Jev for?

He describes Jev as a decision model for high-volume yes-or-no and routing judgments. The source does not give its benchmark score or cost per task.

Do the benchmark rankings establish which model is best for every team?

No. Meyer says the Artificial Analysis Intelligence Index measures general capability and advises readers to shadow-test models on their own workloads before switching.

Source: ThorstenMeyerAI.com

This content is for general information only and is not financial, tax or legal advice. Consult a qualified professional for decisions about your money.
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