When I hear about someone outgrowing a YZF600 or F3 or 600 Kat or something, I always have to wonder. Of all the people I've known and ridden with over the years, I can think of maybe three or four, offhand, who were actually able to use an honest-to-god 100% of even these bikes in anything other than a straight line, and I certainly ain't one of 'em.
My roommate rides an EX250, and has for seven months (I think he's got 2500 miles on it). Every now and again, he'll stop at the bike dealership on the way home, looking at used 600's and think "y'know, it'd be nice to have more power...". But then he turns and looks at the little Ninjette and thinks "...on the other hand, I don't see any drag marks on that centerstand; I haven't even used everything this
bike has to offer yet. I certainly haven't learned everything it can teach me".
I wish he'd hurry up and do so, though, 'cause I want to buy the little 250 from him.
In direct answer to your question, I think a YZF600R or FZR600 would make a better starter bike than an R6 by a long shot. An R6 has rear-wheel horsepower and performance numbers that would've been considered adequate for a literbike just ten years ago, plus it has razor-sharp handling. This sounds like a good thing, in that it'll do whatever you tell it to right now
. The only problem with that is that it'll do whatever you tell it to do right now, even if you tell it to do something wrong. It'd be a lot more beneficial to you in the long run to pick up your basic skills on a more forgiving platform, and we do
want you in this sport for the long run. It gives us more cool people to ride with.