I'm buried but have quite a few threads to post, so please be patient
With an impending move, I took my last opportunity to borrow a friend's '05 R6 this past weekend. I had it for about 24 hours and rode it about 150mi. The only mods are that it was lowered (way down) and had a left-side frame slider.
Compared to my '84 500(cc) Interceptor, here were my notes:
1) Weight is significantly less. Probably obvious, but noteworthy since I think the lighter bike was easier to handle and from a learning perspective that is something that's pretty important.
2) Power was amazing, as we all know. I'm glad I'm experienced b/c this would have been too much for a newb to two wheels.
3) It was MORE comfortable than my 500 which has a more upright position. The reason is that more of the tank was between my legs, offering me more opportunity to grip and balance myself from front to back.
4) No petcock or ability to see into the tank. This was a bit disturbing since I don't typically trust electronic devices to that degree.
5) Distance I could turn the handlebars was far less than was available on my 500. Since its more aggressive and takes more aggressive tires, this was really a non-issue, though turning the 500 around in the garage was far simpler than the R6.
6) Brake level grabs (aka unintentional endos) were a non-issue. Perhaps that's because I practiced lots of late braking on my 500, but the brakes were FAR more powerful here. I still used most of my hand, none of the "one or two fingers" thing.
What I got out of the bike was a recognition that I'm past due to move up. I have no idea at what point I had been wringing the 500 out continuously enough to move on, but I know it was a while ago (maybe last season). I also learned the R6 isn't going to be too much for me, though that doesn't mean I have any interest in liters.
For new riders, I'm not sure how you know when its time to move on. I suppose the rule of thumb I'd suggest is that when you're constantly running the bike at the upper end of the tach and you can take curves pretty aggressively, you're close.
That said, I'm still a strong believer this is the wrong bike for a beginner. Period. Given the the GSXR and ZX6R are effectively the same in power, they would be unsuitable as well