Thinking caps activate. Well, I'm sure most of the staff is well paid...so many probably have both systems at home. At work they'll have lab with minimum 12 Dev kits for each to test multiplayer, so they probably get about equal time on both there. At home, its more likely that bungie staff would have more friends playing on Xbox given the long history of the team. Game runs equally well on both systems so the only obvious difference is the friends lists. So i'd say more employees play on Xbox