I started on a new 2004 SV650S and loved it. I put 23,000 miles on it my first year riding and never went down. I then thought I was ready to move up so I got a new 2006 GSX-R1000 and proceeded to crash it in the first 4 months. You will probably be happier with a 600 over a 250 because you won't feel the need to "move up" or get bored with it so quickly, just make sure you respect the bike and don't over-estimate your abilities. In hind sight, I should have kept the SV another year or two before transitioning to a liter bike, but the SV was so easy to ride it made me over-confident. Anyway, there is my experience with starting out... Just don't try to move up too quickly!