1 of my fav support mech as i have taken down at least 4-6 mechs in few battles and almost all die in my LRM15 rain..
I was going to do a similar set-up. But I'm going with an XL325, ENDO, BAP, TAG, 2 Large Lasers in the arm, the same 3 LRM 15 setup and then I think I crammed in 8 tons of ammo. Only 12 DHS to your 17 though.
For me, it's the lack of BAP and/or TAG. Currently BAP gives you extra range, in the next patch it will prevent ECM lights from stopping you from raining LRMs. TAG nullifies ECM on your target and helps your barrage. I'd drop the MLs and maybe a DHS or 2 to get BAP and TAG, and maybe some more ammo.
Another possibility to shave some additional weight would be to choose a smaller engine, as you'll be firing from the backlines most of the time anyway.
good weapon combo's, and plenty of ammo. I have done a few mods to the engine, but otherwise is quite good. 4-5 stars.