Personally, MCH is decent as it is. The rotations are simple. Everything weaves together seamlessly. Everyone seems to be asking for more complexity. If i were to give my 2 cents on the job it would be as follow~

1. Wildfire - Don't see the problem behind this skill other than reducing it to 90 second cool down from 120. And it does have a purpose beyond Hypercharge for those saying there's no interactivity, etc. You are supposed to use it with the Automaton Queen AND Hypercharge. The Queen's Roller Dash and Arm Punch count as weaponskills. So with 5 Heated Blasts, 1 Heated Split Shot, 1 Roller Dash and 2-3 Arm Punches - you are looking at a potency of 1800-2000. That's some big damage. It would be a nice touch if this skill could crit though.

2. Flamethrower - This skill is boring. Instead of a flamethrower they should have made a flame turret that does the job while you can still use other AOE's.

3. BioBlaster - Remove shared cooldown with Drill. This way MCH have an actual DoT they can place on bosses without sacrificing damage from Drill.

4. Battery OverCharge Mechanic or Heat Transfer - There should be something along the lines of overcharging your battery to 120. This would increase the damage of your Queen and atk speed. Or if you can transfer the heat gauge to your Queen to increase damage and atk speed.