If youre going 2 man then pick a second man that is strong early on. By the time he reaches lvl 15 or so the omnigun will be pumping out death like theres no tomorrow with a variety of deadly gadgets to go with it
. The gadgie suffers from only being able to use a lighning rod and port-o-potty to do any serious damage early game.
Ive never really seen the melee possibilities of gadgies, they will be just ok, a little inferior to bards, and the omnigun will shine later so i always use a modern weapon to raise skill.