im in the same boat.. i also want a 600 for a starter.. my rommate has a 1000 and everyone iknow has started out with a 600.. i too am in the mindset that i dont wanna buy something crappy now until im "used to riding" then sell and buy again.. i catch onto things really fast and personally dont think its a bad idea.. but then again i dont have that much experience either
A GS 500 is NOT a crappy bike, it will still out accelerate almost all of the cars on the road and can go plenty f******* fast, however it would also be a good beginner bike and if you get the f version it will look just like a sportbike.
and ya a "beginner" bike can stunt just fine(once again to prove they aren't crappy bikes)
http://www.youtube.com/watch?v=6MGelSYavwQ
I started out on a GS 500 and really the only reason I upgraded this year is because my old one broke (clutch went boom)
basically
start on a ninja 500, 650 or a gs 500 or sv 650, they will go pretty damn fast and unless your buddies are professionals that also happen to drive like maniacs on the road you will have no problems whatsoever with keeping up with them.
oh yes, insurance on the above mentioned bikes will also be a hell of a lot cheaper than a gixxer.
If you still are gonna be stubborn and insist on a 600 cc sportbike I wish you the best of luck and hope you have fun (we won't hate you for getting it, all we are trying to do is help keep new people from picking something bigger than they should start with, when learning to shoot you don't start with a Barrett M107 just like you shouldn't start with a big high powered race bike) I would recommend the ZZR 600, it's the closest thing to a beginner friendly 600 cc sportbike there is I think