I'll start by saying I've never riddent a 1000, but I have ridden a 750.
If I lived my life in corners, or did frequent track days, the 750 would be in my garage. In my opinion the power of the 750 was perfect, and the power of the 1000 would just never be used/needed through most turns unless you are a pro. I think most of us would have to be concerned with lifting the front before we were out of the turn.
But, my riding consists of a lot of commuting to work, and weekend/evening rides through the country twisties. I go plenty over the speed limit, but there are plenty of dogs, chickens, cows....you name it around here, so you really never go balls to the wall.
Also, I do alot of highway driving, and I appreciate the weight of the busa through high speed traffic, wind gusts from semis etc., although, because of the full fairing, a nice crosswind can really make ya open your eyes
So, that being said, for me, the Busa was the clear choice. Awesome power at 4k around town, and still handles quite quickly through the turns that I do.
I guess it boils down to what you plan on doing with the bike mainly... Kinda funny, "Should I get the Ferrari or Lamborghini? Decisions Decisions".