Honestly the best gunslinger/ mechanist I've ever seen was from a game called Dungeon Fighter Online. The character was a shooter with various guns, flamethrower, and stuff but also called out various robots to come out and do temporary actions. Like a little wind up bot would come out and blow up near the nearest enemy or a flying bot would come by and shoot at your target for a few seconds. In the higher levels you could call down these mechs to really kick ass for like 45 seconds (much like the Bahamut egi for summoners). If mechanist was like this, id be playing it for sure despite its failings.