There are a few points about MCH's button-use that make no sense to me:
  • There's no reason to use Split Shot, Slug Shot, or Clean Shot while under Hypercharge once Heat Blast becomes available, as, in less than an 8-minute downtime-less fight you'd be better off faintly delaying Wildfire on the off-chance you both died and made a further HC timing mistake later than wasting the stacks and thereby drifting ALL scaled CDs by the fractional desync caused.
  • There's virtually no reason to use Scatter Gun over Auto-crossbow, for the same reason (though at least it's Heat is doubled).
  • If we are to have a separate Heat Blast or Auto-crossbow, there's then no reason to learn and slot Hypercharge separately. (We could just learn Heat Blast sooner, give Heat Blast a 1.5s GCD baseline, and have it allow for 4 more free Heatblasts, with Hypercharge being unable to be reentered until 10s later as to prevent accidentally double-gauge-spending.
  • Overdrive cannot be used without a Rook Autoturret or Automaton Queen out anyways, so... why is it a second button?

That said, the bigger issues to me are just that...
  • Split -> Slug -> Clean seem nearly pointless in general with the removal of ammo (and that they'd be so devalued by Drill, Anchor, and Chainsaw anyways even if they were reinvigorated), and
  • For a job that can summon cannons out of the blue, Reassemble still can't so much as change my carbine out for a rifle or shotgun (which could otherwise do much to reinvigorate the spread of Split-Slug-Clean).