I've tried my own version MAL-1R "MehRM" (2xMRM30, 2xLPL, LE315) and it actually works. One thing though: despite the amount of damage you can dish out, you still are spreading damage. In just 4-5 games, 2 or 3 times I actually dished out more than 1000 damage, but I didn't get many kills as I expected. You can deal a tremendous amount of damage in a little time and that's why they are fun to play, but in competitive games I don't think they will be as reliable as in pug games.
Like RACs, MRMs are great at psychological warfare. It's a sudden stream of flashes; that's intimidating enough. Also; pilots never know when the stream is going to end - is it an MRM 10? Is it an MRM 40? And so they back off. I've been using an 2xMRM20 on a Trebuchet, and I've noticed the damage spread pretty significantly. For example; the killshot on a crit Hellbringer was IT'S ENTIRE TORSO. Not CT, or both side torsos. It had no armor left on the torsos, so I pulled the trigger, and it lost everything. So they splash damage like a fat man doing a belly-flop into a pool. But my word are they fun.
Personally I'm using them on my Warhammer 7S, and to be honest - nice stuff to troll enemies onto 200m, on longer lenghs only when enemy isn't focused on you. EDIT: PS - btw I wonder if PGI will implement dedicated for MRM's FCS...
That would be the Apollo FCS, and I don't think that came out until the 3070's. But it would be useful to reduce that spread, definitely.
I've tried another build, this time with a heavy WHM-7S "6R meta try-harder" (2xMRM30, 4xM, LE325), and now I fully understood why I don't like them: they simply spread too much damage compared to meta mechs. Most Dakka and Vomit laser builds will strip your armor in one or two shots, while you need to 2 (most of the times 3) alfa strikes to core any component... In fact, more often than ever, my 4xML had better pinpoint application than my entire swarm of 2xMRM30, even at only 100-150 meters. This could not be an issue on an assault because sometimes you are simply more armored than your opponent, so it will look like that you have won a trade because you cored or made him flee after an alfa strike, but IMHO you are not really contributing to kill someone: IMHO it's better to focus less damage on a single vital component than more damage around 3 or more components.
Don't judge a fish by its ability to climb a tree. Don't judge MRMs by their pinpoint damage. Their whole reason that they exist is to deal massive damage and disruption at the cost of accuracy and increasing facetime. That's why they carry the highest amount of damage/ton of ammo in the game, and deal up to 40 damage for 12+ tons, vs an AC20 dealing 20 for 14++ tons. While it is true, that pinpoint damage is king in MWO, that is wholly attributed to the fact where a system based on relatively random hits gets a non-random factor of player aiming skill. But, if you bring enough murms on your team the sheer damage of the combined weapon systems will open up a mech faster than 3 pinpoint mechs where your team might not hit the same component (due to skill, timing, torso twists, whatever). They are a good addition and have a role, though it might not be meta and you might be more used to being able to take mechs out on your own due to purely hitting the right components. I think my approaching them as a support weapon rather than a weapon to solokill mechs with, they will be much more fun to use for you.
And that's exactly why with the current meta they are not worth it and I don't like them: they are a spray and pray weapon, with a face time long enough for any dakka / laser to focus onto your components and that denies you to focus on any component of your choice (otherwise you are gonna miss part of the strike and waste damage / ammo). It denies me the choice to either go for a kill or cripple a mech (be it a leg, arm with a lot of weapons or a side torso) because pretty much always I have to aim for the center (or where his center torso will be) and pray he goes down or I will strip it of its armor... But with the same or longer exposure time of other lasers. LRMs must face in your direction but don't need exposure: that's why they are both hated and feared. With MRMs, if I poke I can't focus but I can be focused: so while someone is getting his whole armor yellow/orange, I'll have a component with even more damage on my torso. You can't trade properly with MRMs and that sucks in most games. The only scenario where MRMs won't be utterly overperformed by other weapons is during a push/brawl thanks to its damage, in many other context it does not perform enough to be worth it. Even mech that were exposing their backs to me survived 2 alfa strike because I wasn't able to focus damage on the back of their's center torso.
I find that to use MRM's I need to play differently from any other type of build, in that I need to work second line with, say, 5 ERMLs until the late-game, because then most enemies are opened up or almost there, in which case the MRM60 on that build is king. If I get too close early on and try to brawl with MRMs, odds are that I'll lose. When I keep my act together and play properly, I always have a good time using MRMs. If I'm greedy or we get pushed too hard too fast, not so much. I'll agree that pinpoint is better as a whole, it's more effective to be surgical than to beat the fuck out of something with a giant paper fan, but man, papercuts hurt. And you can push a lance back into hiding if you swing your stream of MRMs across them~
Yes, I see MRMs more akin to a missile variant of LBX weapons. Not good for opening armor, but after it's gone, you'll have a lot of missiles to crit that open component and you'll be sure to hit it at least a few times, no matter how much they try to twist. Purely a support weapon and when combined across multiple mechs the pure damage output is incredible, armor or not.
Can I just point out that it isn't entirely useless? The bigger your MRM load the more times you can fire it (Less Heat Strain). If you hit mediums and heavies which are lacking in the armor department, they get hurt the most as they have to rely on dodging, cover and damage control to survive. That and it makes a really dangerous face tanking weapon. The closer you are the less time those MRMs have to spread. Oh what's that? Your timber's left torso is red armor? Here let me fix that for you. 15-20% Heat. Plus there's a couple of oddballs out there that can shoot 1 MRM like a small pulse laser.
Rule of thumb for Mrms. If its too tough to punch through, you'll have to get super close. Sometimes pulling back behind cover.
I run a Flame with some new tech. A UAC/10 in the LT and a MRM 10 in the CT. I made the build to goof around, but it ended up being pretty good. The UAC/10 would chew away the armor, and the MRM would finish them off.