I hate to sound like this, but I distrust any technical comments because well, they're from a guy from Namco USA. His comment to the effect of "wow, look how fast it moves!" is pretty meaningless to me, as just gameplay speed (not framerate, as we know it runs at the standard 60fps for 3D fighters) could be tweaked up and down the scale for most any game regardless of proccessing power. I.E, Tekken 4 -could- be set to play so fast you couldn't even see individual moves come out. US employees of certain Japanese companies traditionally seem to know very little about hard facts and just make vague comments which are assumptions. Personally, my guess is that the faster board is Namco wanting slightly faster hardware to deal with issues such as the bits of slowdown in SC2. However, just because there was some slowdown, didn't mean they toned the game down for the PS2 version - it was the same code. I wouldn't be surprised if Tekken 5 on PS2 is 100% identical and also just uses the same code. For one thing, it doesn't appear to have the particle effects of SC2 which were what slowed things down.
I still remember a guy at Sega of America enthusing that the Saturn version of Virtua Fighter 2 was going to have breakable objects on the ground that you could throw people through and did damage, and he claimed it was because Sega of America polled US players and they said they wanted boxes to throw people through so they told AM2 and AM2 said "Sure, we'll put that in!" He then said if it wasn't for Sega of America's feedback, AM2 would be out of touch with the arcade game scene!