I want mechanist to be in the game, but not under the premise you're designing.
I'm not sure if you realize this, but Mechanist fits a Job more than it fits a class. Unlike "Lancer" which was the name for Final Fantasy Tactic's Dragoon. Mechanist in other Final Fantasy game has had their own characters and mechanics.
When you mention Mechanist I can never get the image of Edgar Figaro with a chainsaw out of my head.
http://fc01.deviantart.net/fs70/f/20...sh-d39qyio.jpg
It's sense evolved around guns as a weapon, which is fine by me - and I expect it will become a branch of Musketeer and counter Musketeer's potential job class: Corsair.