John, four of my riding buddies have had 9s, and I've switched bikes with a couple of them. We all use the same mechanic, also, so I have a bit of insight into more than just how it feels.
The 9 is about 80 lb. lighter, although it didn't feel like quite that much to me.
The 9 has an incredible amount of power from the upper mid-range to top end. The Busa has more, but not all that much more until you hit 140-150mph.
The biggest power difference you will notice is the low end and mid-range. Right off idle the Busa pulls like nothing else on 2 wheels. It makes as much torque at 2500rpm as an R-1 at peak, and the R-1 out-torques your 9.
Set up right, your 9 will turn in better and hold a tight line easier, but the difference is small. The Busa is easy to set up and unbelievably forgiving,considering the power it has.
Of my 4 buddies, only one was able to get his 9 set up (suspension)and keep it that way. Our mechanic says the 9 is one of the most difficult bikes he's worked on to get the suspension right. One guy crashed and gave up riding, one sold his 9 and got a 595 Daytona, one bought a Duck 900SS, and one still has his 9 and loves it.
John, this is not precisely what you asked for, but I thought I'd offer it anyway. You really need to ride both bikes back to back. Comfort wise, the 9's riding position is slightly more relaxed, but not a lot. The Busa can be changed in that area at minimal expense. If you get off the Busa and you aren't convinced instantly, as I was, that nothing else will do, then stay with the 9 or buy a ZX12.
