Well, I can't speak to fenders except to say, I'd put on as "unnoticeable" a fender as possible! The Quick 4 is just too pretty otherwise.

Seriously, tho, I'd probably go w/ whatever looks best to your eye. (assuming any fender will do the job you want it to). I just happen to have a Quick 4 as well. (Regular, men's, XL frame) I just love the bike exactly the way it is. It is/was the only bike I didn't want to change a single thing on.