I think the best thing to do is finagle your way into actually testing a strong-running 250 and see how you like it. It's all up to you to ultimately decide what you want to get, and unless you're out to lay down the law upon the world championship title, I'd say that fun-factor is going to be the greatest of all factors in your decision, even though it's the one that we really can't say anything about. So my recommendation is to get your hands dirty and look for something that really makes you think, "Damn, I wish I didn't have to give this back!" If I was your weight (if only) and was looking to have some fun on the track, I would probably get a 150 for the reason Sachs said - it'd be a good compromise between power and controllability (weight).