Well, for grins and giggles I installed Windows 8 RTM on my laptop. Softimage 2013 SP1 runs ok from what I can see. There's some interface weirdness, such as the top menu bar is pure white and "Softimage 2013.......etc etc." is centered at the top of the screen instead of on the left. I loaded a FaceRobot demo scene & it seemed fine - then I loaded a CrowdFX demo & it too was ok. But I then noticed no matter how many times I reset my layout to Default, when I opened another scene it went back to the FaceRobot layout.
Anyway, in my very limited test it seemed to be ok. I probably won't chance it with my main machine for a while though. -Paul