I have an unmodded 360 and I am planning on getting a modded one in a few days. If I play a game before it is released (Madden or Reach whenever it is leaked) on the modded console and then sync my achievements with my unmodded console, could my gamertag be banned? I was going to keep my profile on a memory card and swap between the two consoles.
It's a possibility. Best thing to do is make a new silver gamertag or offline gamertag and use that one to play early. Of course you can play with your regular gamertag once it is released. It looks kinda fishy if you have achievements for a game that isn't released yet in M$'s eyes. Play it safe.
you will not get your gt banned the only time they banned the gt is when you are gamesaving or last year with forza 3. Just sync your achievement only when the game come out