Open Question: Should I buy a GS500f or GSX-R600?

I want to buy a sports bike, but I'm am a beginner. Which means a GS500f is good bike to start with. However, I went to dealerships and Craig's list and they don't have the GS500f for sale, and also I'm reading post saying that you'll easily outgrown this bike. GSX-R600 is like a racing bike not suitable for beginners, but this bike is so comfortable. I'm a very cautious person I'm not going to touch the highway with my new bike at all (till at least 2 seasons of riding it) just for me to commute around the city streets another words i won' be going more than 30-40mph on the bike. I heard many people have GSX-R as beginner bike and they love and still use it. I'm going to motorcycle school so I'll get some experience from there, but will it be enough from me to handle a GSX-R? I mean there is not a big difference between 500cc to a 600cc engine, right? I'm sorry for the long post I just want a well thought-out answer. Thank you in advanced