The main limitation seems to be that you can only be on one team anyway. Even if you link both your PS3 and 360 games to WTF to dump all your stats there. So for the moment, you must choose whether to be on the 360 or PS3 GAF team.
Would be best if you could join 1 team on each platform, just have a drop down on the site to see the stats of the team you are on for a platform.
Yeah, this is my issue. I'd join a 360 team, but I'm already on a team for my local community (which is mostly on ps3).