If anything changes for MCH, it'll be two things, Base 3 shot combo potencies and shot proc chances without Reload available.

Reloads should be required to do the best DPS but should not be required to do any DPS.

This is likely whats causing dungeon runs to feel slower with MCH's, as well as DPS check phases. Since we are wholly dependent upon Reload and QR to do a full proper 3 shot combo rotation, if our Reload isn't up when we need it most (A DPS check phase for example) then our DPS is extremely poor without very lucky procs.
On Trash mobs, we only have Reload up for the first mob, after that, its RNG time.

My suggestion/thoughts on the matter is simply a boost to baseline potencies (200 potency for our end of chain shot is about as strong as a Tanks second combo strike) while moving Split Shots proc chance to 65% and Slug Shots proc to 75%.
There are many times when we never get to Clean Shot without Reload due to 50% -> 50% chance to reach it. That hurts. I mean hell, ask a DRG to only use the first 2 strikes of his combo chain and see how harshly his damage falls off.

I'm not asking to do more DPS than a DRG/MNK/BLM in full burn, but being within 5%~ is a reasonable thing to ask, especially as our effective DPS gap widens if we want to support our Party. We lose the Turrets damage AND the Physical/Magic Vulnerabilities to give that support, It's only fair to ask that we can keep up with the other DPS when not in a support role.