I find auto-med to be useful as a med kit replacement on most soldiers (leaving rifles with both). It saves too many troops who would bleed out otherwise (you can't always run someone over in time).
Grenade launcher (outdoors only) now reaches far enough to be useful. Still WAY heavy (I take 1 max).
The Machine guns are for suppressing packs and more often, for chewing through bot armor (the to-hits are high enough against bots that you can do serious damage). Collossi are slightly more portable machine guns, but need a med module and be immune to suppression (they get suppressed, they can't even shoot..).
I find up-armored MARS much better than using shield characters: can tank a lot of damage, heals for nothing and instantly, can usually be replaced at half price if it DOES die, carries 6 grenade equivalents (or a big gun for indoor work), can't cause troops to panic.. Use it early, preserve it if it takes serious damage and ALWAYS use the over armor option. Having a triple-shot available can solve a LOT of issues. Oh, and it knocks open doors and removes a lot of walls, letting you mouse hole the cleaner base. Just be careful about sending it through hostile doors and teleporters (it has terrible reflexes and draws all kinds of opportunity fire).