I think MCH needs a lot of love. Granted these are just personal opinions but:
MCH doesn't really get anything except one ability this expansion. Sure you get Scatter Gun but that's basically just a potency and animation increase. But a lot of jobs got that so ... moving on. You also get an attack for your Queen but odds are you are paying more attention to your abilities and fight mechanics and will never see it. So really you only get Chainsaw at 90.
The addition of Reaper to make makes Hypercharge need a rework. Granted I've never liked it but what if Hypercharge upgraded your Shot Weaponskill to their Heated variates, gave you 6 charges at a 1.5s GCD, and upon doing those 6 Heated Shots you get a really big Heat Blast attack. This way all the heated variants could give Battery Guage. Sure it's a lot like Reaper but it's be much more interesting that spamming Heat Blast or Rapid Crossbow 5 times in a row. Speaking of which....
It's AoE needs work. Only having Spread Shot and Bioblaster is just kina atrocious. You also have Flamethrower but I have no idea how often it does damage while you are channeling it or if it's even worth using so... /shrug. I feel like Spread Shot needs to combo into something and then in your Hypercharge phase Spread Shot upgrades to Auto Crossbow? and the other attack would upgrade into Scatter Gun? Maybe make Heat Blast a Single Target with AoE fall off or make Auto Crossbow the Heat Blast equivalent or something.
I've always hated Wildfire and I still say it should be a DoT you place on the boss that deals damage over time and then explodes for the Total damage it dealt.
I think Gauss Round and Ricochet should share timers and if Hypercharge got the above changes remove the effect it has on Gauss and Ricochet. This would also help those with ping issues and the such. (Yes I'm one of them)
The Queen. I think you either need go give the Queen some AoE fall off damage to make it worth using during your AoE phases or give a AoE summon.