Since specialists can use smartguns, do you think it would ever be worth ordering one of them a smartgun system? And when would it be worth it to take it off of a dead corporal?
Scout specialists are right out, since they can't use their cloak and a smartgun at the same time.
Sadar specialists rely heavily on being able to carry rockets, and not having a backpack really hampers them.
Grenadiers could maybe get by as long as they fill up pouches, armor, and webbing for a total of 13 spare nades and 6 in the chamber.
Pyros kinda need their backpack to be able to actually spray flame. But on the other hand, they're not really all that useful so they might as well pretend that they're actually a smartgunner.
Snipers however could do very well with a smartgun, they will miss having a backpack and ammo belt, but they'll still be able to carry 11 spare mags for their sniper and they tend to throw away the ghillie armor anyway.