For what its worth I passed my MSF course in Pennsylvania in late June and got a Ninja 250 09 a week later. I can say if you have no experience riding the 250 can accelerate very quickly. I am 5’11” and 212lbs and it will get up to 55mph with no problem and I am conservative on the throttle since I am in the break in period for the engine. I was thinking that a used 500 or 650 would be better buy in the few trips I have made with my new bike I have come across situations where more hp would not be helpful.
The new 250 looks great and I found little difference between the ninja 250 and 500 as far as fit goes but their is a huge difference to the ninja 650 ( much more up right and much heavier). I know that a used bike is cheaper than new for insurance and initial cost but if you are not mechanically savy to recognize problems buying used can be difficult especially without help. Good luck finding your ride!