Fable can solve the problems Opus couldn't. BUT most of the time I'm not having those kinds of problems.

I wouldn't say I'm doing anything groundbreaking but definitely at times obscure and that's when Fable has been able to dig me out of the rut. (the alternative I was actually following was reading textbooks myself to understand the domain better)

The weird twist here is that I've found that there are times where Fable is actually worse than Opus at a straightforward task, not just more expensive. It'll launch off into its own little world for an extended thinking, then start editing files, and I'll already have spent $5 in tokens before I see enough response to know that it's on the wrong track.

Opus's verbosity is actually a boon sometimes for catching false starts early.