TotalChaos, I understand what you mean, and I agree...I probably wouldnt get a brand new GSXR600 either.

As far as comfortablity of an R6...

Im 5'10"/155 lbs...and my 2002 R6 is very comfy. The seating position of the 2003's are not significantly different from the 2002's. It is not too agressive of a seating position...so you dont have to make a huge effort to reach the handle bars. The gas tank is not too wide or too high. And the foot pegs are not too high and not too far back. I think the seating position is the perfect balance between comfort and sportiness. The seat is not too wide and not too hard. As far as handling...I feel the R6 handles the best because it is the lightest of the 600 class.

Ive never sat on a new CBR, but the 2002 and below have hard seats. Hurts your ass after a good amount of riding. Seating position is not extremely aggressive or too mild.

Ive never sat on a new Ninja, but the 2002 and below have a wide gas tank, and my inner thigh muscles hurt after alittle bit of riding. Seating position is pretty aggressive.

As far as the GSXR600's the seat is nice, and the gas tank is a good size...but out of all 4 bikes, I think you have to make the biggest effort to reach the handle bars. The pegs on it feel slightly higher than that of the R6 on this bike. My thighs are more horizontal when sitting on this bike, as compared to the R6. The seating position of the GSXR600 is the most agressive. If that is what you like, thats cool. After riding for about an hour straight, my lower back was slightly sore. This bike felt like it had the most aggressive position. I was leaned forward pretty far when just cruising on this bike.

In general the GSXR and Ninja have the more aggressive seating positions, while the R6 and the CBR have a more mild seating position.

You should sit on all of them. Depending on your height, you may not have the same problems or thoughts that I have above.