[MusashiStyle]

well I think that 7-tabling reduces variance over the long run, suppose u have a ridiculous downswing while 7-tabling.
and u lose 7 buyins. Now suppose u r 2 tabling and u have a ridiculous downswing: u lose 2 buyins over the same time period u would have lost 7 buyins.
Actually it's a bit more complicated thatn that because u could easily lose 7 buyins while 2 tabling if u run badly enough as well.
I think the critical reason why I want to have more buy-ins when I am 7-tabling is not increased variance but rather the fact that any sort of serious tilt could be more dangerous when I have more tables open and less time to think about each decision.
OF course if there is such a danger I shouldn't be 7-tabling in the first place. But I think it's a sort of complex question and I'm still not sure what the correct answer is.