The Busa is heavier and not nearly as fun. The new GSXR1000 and new 10R are very comparable. I would recommend sitting on the 2 of them and see which one sits and feels better for you. The 10R has more grunt, more ram-air "howl" to it, and I think is more agressive for riding. The GSXR is going to be redesigned again next year keep in mind.
Send a pm to "snake" on the forum, he has ridden both.
I ride an 06 ZX-10R and am really happy with it. At 5'7" and 150 lbs the Busa is a little bulky for me. I'm sure the GSXR is a great bike as well but I don't personally care for the styling. Bottom line I'd just try to get a quick ride on both and see which one you prefer. Either bike will perform better than 99% of us could ever hope to ride.
I'm 6'6" and 230 lbs. The 10R is a much more comfortable bike for any rider, even the taller ones. Actually, probably the most comfortable litre bike for tall riders, and longer trips don't aggravate anything.