In IGN's SSX3 head-to-head the Xbox came out on top for graphics with GC second and PS2 third. In every head-to-head I've read the PS2 always has a more flutuating framerate than the other consoles and the load times are unbelievably longer.
I have compared the games with my own eyes, on the same TV set, and I can flat out tell you, IGN has no clue what they are talking about. PS2 version has extra lighting effects not found in the other two (a very nice glare effect when you exit the caves, etc) and is otherwise *identical* looking, 480p and all. Framerate dips are present in all three versions, and occurs seldomly at exactly one course in the game (the night city track). I'm betting the problem with some of those head-to-head comparisions was the fact that EA hasn't even said to annyone that PS2 version supports the 480p, until almost a week after the game shipped to stores. There is no mention of it even in the manual. Besides, there are so many misjudgments in those head to head comparisions that they are not even worth reading, IMO. They can't even tell the actual framerate most of the time, much less notice other differences.
IGN's assessment of load times in the PS2 version is completely and utterly wrong, as well, which 15 seconds spent with a stopwatch can tell you. I could not believe what they were talking about there, when I saw that the load times they measured for the GC version were pretty much exactly what I measured for the PS2 version with a variance of +-1 second.