IGN stated that graphically speaking, all versions will be near identical. So if the frame rate on the GC version is a near enough rock solid 60 with occasional drops below it (the 60fs also applies for multiplayer), then it may be the case for the other versions. IGN also said that most the editors found the GC controller best for TS2 (in one of the TS2 articles).
There won't be any online facilities on any of the version, though there will be a feature that allows you to link up multiple consoles on both the PS2 and Xbox version. So IF you're interested in getting around 8 friends together, and you have the option of hooking more than 1 console up, then go for either the Xbox or PS2 version. If you're interested in better controlls and possibly a better frame rate (not sure), and will only ever have the option of playin 4 player, then go for the GC version.
__________________
|