I’ve been going back and forth between opus and local Qwen 27B and a good number of times opus makes absolutely stupid things compared to Qwen.

For a large number of tasks you definitely don’t need a frontier model but a good harness around it.

If you don’t can’t/want to experiment with local model, have Claude implement the exact same feature with haiku/sonnet/opus and see what the differences are. You might be surprised.

I've used extensively everything between Opus 4.6, GPT-5.5, Fable 5, Opus 5, GPT-5.6 Sol, GPT-6 Astra, 6.1 Sol and Opus 5.5.

To a lesser degree also Sonnet and Luna.

And when I say extensively I mean 500h+ on a side project in addition to my full-time job.

Even the difference between 5.6 Sol, which is miles ahead of local Qwen 3.8 27B, and Opus 5.5 is immediately obvious in the quality of the results.

Having been stuck on 5.6 Sol at my job while Opus 5.5 was available at home, I can say with full confidence that the difference is significant, even if I weren't looking at the output at all.

The way it understands my requests, forms a hypothesis, verifies the result and finishes the change is night and day different. This happens while 5.6 Sol is still flailing around somewhere in the monorepo struggling with even locating the relevant code.