This is what I used for grinding all 3 variants. Getting the -s version first means you only need replace the one arm to get 2 energy and 2 MG slots, plus ECM. Since this is a firepower build, it has no AMS. LPL's have great range (600-1200), and the amount of time you need to hold them on target is no longer than IS ERLL's, which is important when you're squishy and people want to shoot your ECM arm off. You have the range to score high assists and the damage/MG crits to get kills and component destruction XP. Don't forget to occasionally jam enemy ECM to get ECM Jam XP. To provide ECM coverage, you have to be effective at most ranges because you don't pick where the center of the blob is. The arms let you shoot around the sides of buildings, but are terrible for poptarting, especially with convergence issues. You won't go far wrong in fighting the Kit Fox like it was a medium mech instead of a light: Let the assaults and heavies go first, then hit their target. Keep moving, don't lose an arm. Peek around obsticles, preferably with the left arm so you don't lose the ECM if they shoot that off. 21+ damage at 600 range is no joke. Use the MG's only when an enemy is badly wounded and you are going in for the component destruction and kill, for more exp. Recommended weapon groups: Group 1(Mouse1):Left cLPL Group 2(Mouse2):Right cLPL Group 3(Mouse3):Both cMG's For the aforementioned peeking around corners.
I just realized this is in the wrong section, I'd seen the other build here and thought it odd that there weren't more builds. Could a Mod move it or delete it if it's redundant?
Honestly I think this would be a better option. You have to buy/have the Prime arm but you have the same firepower for less weight, giving you room for more jumpjets, ammo, and heat sinks. The left arm is rather low to the ground anyway and isn't conducive to synergistic sniping with the right one.
I have a similar build. Ecm, 2 lp, 2 mg, 4 jump jets. I am only using it to xp the chassis but it is nice. Just killed a dire wolf and dragon while assisting with 7 others. 489 damage and I was only one left, 12-11 match (killed dragon which was last enemy).