I dont think that feeling is entirely useful.

Because Claude doesn't allow third party harnesses on their subscriptions I doubt the majority of signals you're getting are actually that significant on pure model quality.

I suspect you're right on Sol not outperforming Fable; but i've not used Fable that much.

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But, fwiw, in my custom harness between Sol & Opus 4.8 - then Sol wins by a ridiculous margin as Opus keeps claiming slightly wrong things with certainty much more.