That's the thing though...Am I at 30 buyins, or at 7.5 buyins (3000/400)?
You are at 30. Someone correct me if I'm wrong but I think the general consensus is that you shouldn't need a larger bankroll because you are multi-tabling.
Wikipedia is the best thing ever. Anyone in the world can write anything they want about any subject. So you know you are getting the best possible information.