for a support gun there's not really much call for anything more than your basic contact-saving mosfet.
motor wise as mentioned above brushless would be an option for more longevity, certainly make servicing a bit cleaner what with not spewing carbon everywhere.
rof wise there's arguments that speed chasing on an lmg is counter productive, and will in any case be likely more limited by the magazine than the gearbox.
as with any gun it'll benefit from a good consistent air seal, but given the higher ammo consumption of support guns lot of folks won't be running the heavies for cost reasons which would put a ceiling on how far it's worth chasing perfect accuracy.