My classic remix of a TBR-Prime stock loadout with a focus on beating the shit out of IS mech's before their abundance of DPS and equal range can really destroy you. Beware the HLLs while brawling, since their heat adds up real quick. Use the paired lasers together at mid range, and stick to the MPLs with the close range weapons unless you need to kill something right-the-fuck-now, override engaged. *EDIT* I've dropped the HMGs in favor of LMGs for the range. 1.5 tons of MG ammo is plenty, the main use is just to barrage whatever you're focusing on, since people seem to dislike the sound of machine gun fire hitting them.
Just to my taste, I'd probably drop the HMGs and ammo to give more ammo to the SRM's; 4 weapon groups is kind of a lot for me.
Yeah, 4 can be too many depending on how controls are layed out. I actually use my spacebar as group 4, which I find works best for SRMs, and the other three to be on my mouse. Modified as seen fit~ The most I've tried to run with is 5 weapon groups, but that was definitely way too many.