i'd love to get a set that didn't actually screw into my frame, as i'd like to avoid any chance of getting scratches on it
I am, by no means, a fender expert. (or even user for that matter)
My thoughts on the mounting though, are that a securely fastened (ie. bolted on) fender will move arround less and cause less damage to the bike.
If anyone who has experience in this regard would like to correct me, it may influence future fender buying decisions. (I'm starting to like the idea of fenders.)