Baseline yeah. But part of the reason you run open models is how much nicer fine tuning them is. Granted, you probably don't want to try and make LoRAs on a 4x RTX6000 setup, but you could if you really wanted to and there are other ways to modify models. And yes, if you're good at it, you can turn a piddly mid-range model that's only good at benchmarks into a heavyweight clanker (for a specific domain).

Well, they are if you're into animating pelicans. :-P But yes, in the general case Opus is a better match.

And Opus is no slouch. I'm satisfied that GLM 5.3 is just as strong as Opus. Z.AI has promised/bragged that they will be at Fable 5.0 level by the end of the year or early next year, and I don't see any reason to doubt them.