Nearly every re-release on XBLA is altered for at least HD support, if not all. Several add in online multi-player, and even some add in even more. The idea is that probably two or three VC games seem modified at all, whereas all XBLA games are. Chances are the XBLA version would be better. Not necessarily, though, as the deal might prohibit changes made to the software, or allow both sides to exploit said changes for their own benefit.