(Apologies, I will need some tutelage on how to format the image and link properly - I tried to locate the FAQ/explanation but was unable.) This is my take on the 3N with the new tech. And boy oh boy is it fun! Fire groups are: 1: Left RAC5, 2: Right RAC5, 3: 4xML. So depending on the situation you can either spool up both RAC's and unload until they jam, or fire with one, spool up #2, and thus keep a near continuous suppression dakka on your enemy's face. Generally though you want to fire in bursts of both RAC5's as much as possible. Having left/right unique though gives you some better left/right poking control. And believe me, keeping two RAC5's on an enemy mech gets their attention big time. And also nearly completely suppresses their ability to return fire on you or any teammates. Cons: you're still running an XL, so you have to be extremely cautious and pick your engagements carefully. Still very much a support mech, although you can go toe to toe in some situations. Secondly, if you are not careful, you can definitely run hot. Go for the double cool shots and double artillery strikes on the skill tree. Possible alternates: swap out the AMS for more leg armor. Although, in my games so far, people rarely go for your legs, but usually try to pop a torso. Also, given your over-hill poking ability, your legs are often well protected by cover.
I use a slight variation of this build being I am not a fan of IS XL engines. Man, I love playing this mech!