At 6'-3" you'll have a problem with just about any sport bike. Which gets back to my original point, no one needs even an R6/GSXR600/ZX6 etc on the street. If you want to do track days or race then fine, buy one. Otherwise you're just wasting your money on power and ability you'll never use or need. Buy something less racy and use the money you save to do something like the Code School or similar. The skills you learn will make you far faster (and safer for that matter) than a different bike.
I'd say I use about 40% of the capability of my bike generally speaking and have no real desire to explore the remaining 60%. The margins are thin enough without pushing it. Heck, I rode it in this morning and on the on ramp to the highway I decided I'd let it breath a bit. On the shift from second to third I was pushing 75 with another 3 grand towards redline. On a sport bike I'd have been pushing triple digits which is just plain stupid.