Any person who would choose 3.7 with a fancy harness has a very poor memory about how dramatically the model capabilities have improved between then and now.
3.7 was kinda dumb, it was good at vibe UIs but really bad at a lot of things and it would lie and hack rewards a LOT. The difference with Opus 4.5 is that when you go off the Claude happy path, it holds together pretty well. With Sonnet (particularly <=4) if you went off the happy path things got bad in a hurry.
But skills do improve model performance, OpenAI posted some examples of how it massively juiced up their results on some benchmarks.
It's not.
I've done this (although not with all these tools).
For a reasonable sized project it's easy to tell the difference in quality between say Grok-4.1-Fast (30 on AA Coding Index) and Sonnet 4.5 (37 on AA).
Sonnet 3.7 scores 27. No way I'm touching that.
Opus 4.5 scores 46 and it's easy to see that difference. Give the models something with high cyclomtric complexity or complex dependency chains and Grok-4.1-Fast falls to bits, Opus 4.5 solves things.