Let me preface this by saying I have been using and raiding on MCH since 3.0 (Yes, when it was straight garbage.) So I feel as if I have a general idea of how the class works and feels fundamentally enough to talk about its overall balance. I personally love the way new MCH plays, just have some minor gripes with its overall current placement.
4.0 MCH saw a lot of down tuning in terms of its performance form 3.57. Hypercharge was reduced from 10% → 5%. A lot of its oGCD skills were taken away and a couple that remain on MCH or as role skills, lost their potency. This lowers MCH overall burst quite a bit. Now, while we did receive some good things such as the heat gauge and an overall new play style, a few things about it make MCH quite a bit much to handle.
Heat Gauge
The heat gauge once at 50h, will turn the basic 1 2 3 to heated 1 2 3. This adds 30 potency to each one. Cool. Now the issue comes down to during progression, or screwing up in a fight, MCH has a rather hefty punishment with losing the heat gauge. 10 seconds of no GB being the first thing, then a 9 GCD build up if you do not have flamethrower or barrel stabilizer available. 9 GCDs. Its quite easy to say, well don't mess up the heat. In the middle of a fight or something happens, you die etc. There are just times where heat cannot be maintained properly. Now in the event that you do lose heat without having a way to recover, you cannot reload. If you reload you extend the GCD count to return to 50 heat by 3 with quick reload extending this by 2. That makes a total of 12~15 GCDs. So not only do we lose access to heated skills and have to ramp back up, we are further punished by not being allowed to use ammo while recovering. Now you may say, why would those heat recovering skill be on cooldown? Because we use them to get higher DPS.
Also, if possible that we ever get toned down job gauges, make heat gauge a bar. Would be easy to pay attention to than a weird wheel on my screen. Minor gripe.
Now lets look at
Utility
With the addition of 4.0 MCH main utility in hyper charge was reduced from 10% down to 5% BUT gained the ability to boost ALL damage now. This boon is debatable but seeing how a lot of classes got their support tuned down we will just call this one okay. Dismantle now has the ability to reduce all damage by 10% for 5s, to include darkness damage. This is also good. Refresh and Tactician will not be mentioned because both BRD and MCH have those.
When compared to BRD, they have 2% crit up for party so long as their songs are playing (all the time), they have 15% direct hit buff from battle voice, and a 3% all dmg up for 24s every 150s. They have troubadour which does 15% HP, 10% physical dmg down, 10% magic dmg down depending on the song used. Natures minne is a single target mantra 20% healing up. They also have Wardens Paeon which is effectively an Esuna.
Comparison
When looking at both BRD and MCH you would say, one is more support oriented, while the other is more damage oriented. In my mind that is how I believe they were supposed to function in 4.0. BRD a bit lower DPS with higher utility. MCH lower utility higher personal DPS. That is currently not how things are looking. BRD edges MCH out a bit on ST, which only gets worse when they are allowed to multi dot. See Lakshmi EX. It makes no sense for one class to have more personal DPS, raid DPS and more raid utility options.
Proposals
So the issues with MCH are as follows, bad recovery in the event of death, or unfortunate overheat. Lower overall utility, and lower personal DPS than its ranged brethren BRD. A few proposals to fix the class to bring it up to where I think it should be. As many MCH playing the class do indeed feel what I'm talking about. Its weak.
Flamethrower. Sometimes it randomly cancels. Thats really annoying. Yes its clunky, that's not the problem with it. Its weak. 60 potency aoe that halts auto attacks and build 10h each second (start up gives a tick of dmg and heat). Let auto attacks go through FT or buff the potency to 80.
Barrel Stabilizer. This skill is good, but it is also MCHs gate. The current skill has a 120s cooldown. This effectively halts you from overheating all your wildfires because you lack recover afterwards. Cooldown lowered to 60s to allow more stable recover after accidental overheats or deaths. Also has a little bit of delay on pull before can be used (annoying).
Gauss Barrel. Nothing is wrong with the skill itself but how it is now handled. When you die, or go into an instance, GB is taken off. This is annoying for MCH who have been playing the class since 3.0. Starting fights while forgetting to put GB on after each pull. Also, lack of GB icon. You have no idea how many times I have turned gauss barrel off because I thought it wasn't on. Put the icon back please.
Ammo. Ammo itself is fine, but there are times I wish there was a way to dump ammo. Literally just toss it out of my gun. Click off whatever. Why would you want that? There are certain funny situations where you just wish you didn't reload. If you play MCH you would understand. Phase change where you wanted to use the ammo but weren't able to get the gcd off, so now you are behind on heat because you have to hit the boss with an ammo'd attack where you wanted it to be used before etc. Lots of situations. With the changes to the way ammo works, a way to give up ammo would be nice. Also, ammo icon. Give it back.
Split, Slug, Clean generate 10h instead of 5h when below 50h to help with recovery. 9 GCDs down to 5.
Hot shot. 10% dmg please.
Wildfire. 30%~35% dmg instead of 25%.
Overheat. 20% increase instead of 10%.
These are changes I believe will make MCH powerful but not god tier as it was in 3.57. Overall this should keep them below casters but above BRD, which is where they should be.
4.0 MCH is a lot nicer to play visually and fundamentally. The way the class flows and feels is excellent. The only issue is lack of damage compared to lack of support vs BRD and heat recovery and how punishing it can be.
P.S. Put disembowel back to 10% to help out our poor DRG friends.
PSA: Bidoof Jihn of Odin figured out the source of flamethrower canceling.
"I was wondering lately why I kept getting my Flamethrower cancelled in Dungeons and did some testing.
I figured out that ever since they changed AAs back in HW, they added this "Auto-Tracking" on the target you're casting or using an Action on. Now the thing is that even if you untarget the mob and then do Flamethrower, it still kinda "snaps" onto the first mob hit.
So basically, you'd do flamethrower and everything's fine, but suddenly your target moves. Now what happens is that Flamethrower doesn't allow you to turn, which means the "auto-tracking" on your target cancels it. Now I haven't done testing on the Samurai Ability "Meditate" but I think it's the case for that one too, as I accidently got it cancelled once while doing it in PotD.
I'd assume this isn't quite working as intended, as it's almost impossible to get it to work reliably in the situations you want it to work, and I hope this might be seen by the devs."
as of 4.01 Flamethrower shenanigans have been fixed.