Technically the Japanese server has a few perks that the NA server doesn't, such as the ability to send PMs and have multiple screennames. However, this a hardly important anyway.
Touching on that; the funny thing is that the original Capcom servers for NA didn't regulate how many usernames you could have per email account, nor did creating an account require confirmation... so people could keep creating as many usernames as they wanted. It was pretty hilariously broken. So broken, might I add, that several people could be logged on to the same username at once and they would not be booted from the lobby/game.
I know that Fog would probably have to implement a different system. Probably the same one that he's got now... which would kind of blow butts since yeah -- one username due to SNAP not being as hi-tech as KDDI. Oh wells. It'll keep me from having my ever-so-often name-change crisis where I have some new stupid username for fun.