Being a motorcyclist myself, and having both a carbed bike, and a FI bike... if you don't get anything fuel injected, you're ASKING for trouble. They're a huge pain in the ass, and its been a few years since I was on the market for a bike, but the 250's tended to be carb still. Do your research on that first, FI is definitely worth it.
Are you talking about the kawa and yamaha or the ninjette and honda 250? Id go with the Honda since its updated with fuel injection, I like the instruments better, eides well at low and mid rpms(or so I hear). Don't know why kawasaki has not fuel injected the american ninjette when they do in Europe.