As I have some mechs I've always run as LRM boats, it makes their stats fairly comparable to other non-LRM configs.
TLDR.
My conclusing is good LRM boats can work really nice compare to their non-LRM competiors.
Namely Archer-5W with 9xLRM5, Warhawk-B with 4xLRM15 +4 medium pulse, Supernova-A with the same config except with artemis, and two Stalkers other with 4 missile hardpoints and other with 5. The other Stalker is not good enough to fit into first picture.
The Warhawk I've always run with LRMs, initially with 4xLRM15 which then often in a good game I would run out of ammo.I think it had about 2200 missiles. I've alternated that with 4xLRM10 which can carry more ammo and rarely would run out of LRMs. Both configs have had the 4 med pulse. After skill tree, the nodes boosts the amount of ammo so nicely that 4xLRM15 is quite a must, LRM10 is no longer a valid option unless you'd upgrade the med pulse with something much heavier, and then you might need to take LRM5 even.
The Archer 5W has always had it's 9xLRM5 with mostly XL340. I haven't run it much anymore in QP, and it's stats have dropped as I often have it on FP deck. In QP only it used to have about 1.2 W/L rate. For a little time I also tried to carry a narc on the hand but it was too difficult to narc anyone, plus the narcing required quite much more exposure that the Archer could handle.
The Stalkers have been a clear letdown, compared to really any other LRM boat, they struggle. I've run them with varying configs but always max amount of LRM lauchers and often a powerful XL engine.
The Highlander IIC-B shows what doesn't work. It has had configs like 4xLRM20 plus tag or 2xER-L. It can be top by average damage but it's W/L rate is poor.
Im currely trying it out with gauss+2 ERL plus 4xLRM, which makes it something else than LRM boat.
Compare these W/L rates which I think is much more important factor than average damage or kills or K/D rate, to my best non-LRM mechs:
Marauder IIC-D. I've mostly had it with ECM, 2xgauss, 2x-ERL. I've alternated the 2xERL with one PPC. It is very capable mech which is very flexible and non-dependant. Bad map or bad team, doesn't matter, it can do it's thing pretty much always.
Ebon Jaguar, my newest mech. Well, 2 PPCs and gauss on the torso boxes clearly work. If it were my 5th or maybe 10th mech I would probably use different omnipods and try out all sorts of diferent configs. But I've already done all that so that config is pretty much the only I haven't do as it's not possible with Summoner, Mad Dog or Hellbringer. Although 43 games is not a lot but I think it's a clear performer.
Nova-A, probably worth mentioning too. I've always had it with 2 PPCs and some AMS. It has a special feature unlike most clan omnimechs that it can have sideways movement of PPCs. Nice jump sniper, though I can't jumpsnipe from long range.
Some mechs like Catapult or Mauler I've mostly run in FP and the rest have had different loadouts in their history making their stats meaningless.
The first picture is sorted by W/L rate, second by average damage.
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So my conclusing is good LRM boats can work really nice compare to their non-LRM competiors.