They will not reset your gamerscore, but you'll never be able to play online with the gamertag that gets banned. The email also stated that in the near future bypassing licenses from anything purchased on the marketplace will result in a console ban.
So, if anyone has done this, I suggest buying the games and or whatever is it you got, so it looks like you did everything legit. All it takes is one person to file a complaint and you're history.
Figured I would post this because I know a few people on the site that have done this. Just a heads up.