I see 3 main problems with Commando/merc healers.
1) Very tight ammo/heat management. I don't ask for the god mode of 1.0, but something among the lines of diagnostic scan of scoundrels, maybe getting a bit of ammo everytime a hammershot crits? and some free heals to deal with the interrupt hell on PvP, maybe by lowering to half the Cooldown of bacta infusion. I don't ask to be instant, but the current cooldown is looong.
2) Most of the skills can (and will) be interrupted. Since people learned to interrupt, casting classes are at loss on PvP, and some PvE fight with intense knockbacks and interrupts. and we are not very mobile healers, the only heal we can throw at the moment on the run, is kolto bomb and bacta infusion.
3) in Ops, we could use an AoE stronger skill, or at least, a HoT like kolto probe that can be casted on various members of the group.