Opus 4.8 would spend like 10 minutes thinking and then go out there and do an excellent job. Only Fable 5 seems to be smart enough to just know everything it needs to immediately start working without any reasoning or verification. Opus 5 tries to be relentless like Fable, but it's not as smart as Fable and I have to constantly challenge and correct its unfounded assumptions. Sol is somewhere between Fable and Opus 5, it's smart but it's not Fable, it keeps making assumptions that I have to correct.
After trying all these models, I find that I miss Opus 4.8's overthinking. Sure it's slow, but it actually gets things right.