I love the new cbr1000's, and liter bikes are very tempting...BUT....
I know that I CANNOT ride a 1000cc bike at or near its limits. I dont think there are many people who can. I personally thought very hard about going to a 1000 but becided that until i can ride every once out of my 600 I wont change, Its just foolish.
I have a 2003 Cbr600rr I ride every day, its my daily driver now even in the winter and I love it! Im a honda man (motorcycles) , they are so smooth and well built. R6 & R1 I havent heard to many good things about from my friends, lots of problems; electrical, oil starvation, rattles etc.
If i was buying a bike for 5K I would be looking at 03-04 cbr6000rr's or 2004+ gsx-r 600's