Isn't ranged, gun-like gameplay already addressed vis-a-vis the crossbow and--to a more abstract extent--wands? If you don't feel it is, how do you feel gun gameplay could be different from the current ranged weapons in the game?
It'd use only one weapon slot instead of two, that short phrase already answered your whole post.
Since that's your only consideration, it sounds like wands might be a weapon type you'd enjoy. If you haven't already, you should try playing with wands--they can be quite fun!
Regarding the bit where you said "that short phrase already answered your whole post", I'm afraid that I'm confused by your statement. Which "short phrase" are you referring to, and what part of my "whole post" was it meant to answer?