on the not buying a new bike. You're going to drop it and trust me, dropping a used bike is MUCH less painful than dropping a brand new bike. Hopefully you saying that a 250 is not for you is not because you care what people think about you being on a 250... because buying a bike for what other people think is not a good reason to buy a bike. If a 250 is what fits you the best for you to get going, you can always upgrade down the road (like others have already said). But, with that said, I started on a 95 F3 9 years ago and I don't think that was a wrong decision for me. I'm only 5'4" and have not had a problem with my F3, F4i, 600RR or 1000RR being too tall for me (none of them lowered). (well, maybe a little on the 1000 as I need my BF to back it up for me out of parking spots because it would take me much longer to do it on my own
.) I think a 600RR might be too much bike as a first bike and would recommend an early '00 F series or another similar bike. Most dealerships are fine (from my experience) with people test riding used bikes before buying. Try asking friends if you can ride theirs around the block to get a feeling of each different bike. You won't know what you like until you try it on for size
Good luck!