Agree with slvoid. The fx is gonna be quite a bit faster. But that's a pretty steep difference in price. The SU200 "looks" more urban (dark color, thicker tires, less nimble makes it look more urban to me?) but I'm guessing it's at least a few pounds heavier.

You can get the 7.5fx with disc brakes if that's the concern...but I'm often slowing down from 30 to a dead stop and have no prob with the standard brakeset.

Last piece of advice: Go with feel rather than looks, and ride them both before you shell out the cash.