I am 5'9", 135 lbs, muscular frame. I want to get a sport bike, and I know some say that the 600 is too big to start on, but I have ridden dirt bikes, bicycles, pocket bikes, you name it all my life. I am very talented when it comes to motorcycles. I think that I could handle a 600, and I also think that a 250 might not have the power I am looking for. What do you think?