Powerslide, which is an unreleased game that utilized the Super FX chip, currently does not work in Zsnes. The rom was released a couple of days ago. Once loaded up, you can get past the intro screen, though it is unplayable beyond that. The prototype contains a GSU-1A, which I believe is a previously unknown Super FX variant. The date stamp on the GSU-1A chip is earlier than the date stamps on GSU-1 games that I have (Dirt Trax FX and Dirt Racer), though only by a few weeks.
Here is an image of the PCB:
