[nath]

I don't know any of the math behind any of this. What I do know is that I play the first hour aggressively (sometimes maniacally) and rebuy every time I bust, because I need a giant stack to survive the second hour and go deep. I don't play outside of my bankroll and I don't play if I can't afford to rebuy.
It seems logical to me that playing a rebuy when you can't rebuy puts you at an automatic disadvantage to everyone else in the tournament.
Since my results support this method I will continue to use it.