I did a variation of this, so far it is working well. I swapped the right arm for the C arm, ER Lrg Laser, ECM, 2x LRM15, and S right torso for 1 JJ and rest of space is used on ammo (something like 450ish LRM missiles) - but it has done ok for me. I am not the best pilot to begin with, so I have survived most of my matches and gotten a kill and tons of assists in the 4-5 matches played so far. For me it is a good design, but I like my Prime with 3x ER ML and 1xLB5X.
I've been playing with a variant of this build lately. I dropped one of the LRMs to 10 in order to pick up ECM. Nice for escorting the fatties or giving me something to do while spotting.