the latest version of scummVM now supports Myst, and it allows you to skip cutscenes without modifying the game. this makes it the fastest version for speedrunning all pages.
as for any%, it's probably not faster than GOG even with cutscene skips because the fireplace animations now play at the correct speed, making them slower. loading times are also longer across the board. if you want a comparison, the fastest time i've been able to get on scummvm has been a 55 (compared to my improveable 53 PB on GOG).
i'm probably going to do any% runs on scummvm from now on anyways just because it's just a way better conversion compared to GOG and doesn't crash all the time for no reason.
i know there's probably someone who's going to wonder if we should be allowing scummvm to be used for speedruns even though it's third party software not created by Cyan, but honestly the scummvm devs have put way more thought and effort into this conversion than Cyan ever have in their modern conversions, so it should be allowed in my opinion.
So, I think that not allowing scummVm would be a tragedy against the game, since it's difficult enough as it is to use OG Myst on modern machines. We'd definitely get more runners interested in the game, and if cutscene skipping is allowed/ a necessity, then this only makes it better. In my opinion, scummVm is as legitimate as playing the regular game.