Pawel Huryn · 4 min read · AI & Product
Stop Overpaying for Your AI Subscription: GPT-6.1 Sol, Sonnet 5.5, Opus 5.5
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A hands-on benchmark comparing new AI models (GPT-6.1 Sol, Sonnet 5.5, Opus 5.5) on real coding tasks reveals significant performance-to-cost tradeoffs. The analysis also breaks down the true value of AI subscriptions by measuring actual API costs burned through various subscription tiers, exposing surprising differences in subsidy levels across providers.
Key Takeaways
- Opus 5.5 nearly matches Fable 5.1 performance at two-thirds the cost ($58.53 vs $87.18), making Fable 5.1 hard to justify for most users
- GPT-6.1 Sol is over 10x cheaper than GPT-5.6 Sol on complex tasks, largely due to fewer turns needed and cheaper cache reads (4x cheaper than predecessor)
- In long agentic sessions, cache read pricing dominates total cost—Sonnet 5.5 and Opus 5.5 have identical cache read prices ($0.20/MTok), narrowing their real-world cost gap
- Subscription value varies dramatically by provider: Grok's SuperGrok offers the highest subsidy multiplier (18.5x vs OpenAI's), followed by Muse Code (with data sharing) and then OpenAI
- Anthropic's Max plans offer 2-4x bigger multipliers than OpenAI, but GPT-6.1 Sol's lower base pricing still makes it cheaper than Opus 5.5 in practice
Excerpt
Hey, Paweł here. I’ve been sick, so please expect the next standard post on Sunday. Today, I have a few interesting findings to share. Let’s dive in. 1. My Benchmark: GPT-6.1 Sol, Sonnet 5.5, and Opus 5.5 First off, new models. Just recently Opus 5.5, Sonnet 5.5, and GPT-6.1 Sol dropped. I don’t trust the benchmarks, so I tested those models on real work: 2 repos, 105 bugs frontier models missed at the beginning of 2026, find and fix what you can. The results: Source: Bug Hunt Benchmark. Full results and more models. What drew my attention: Opus 5.5 is…