I was gunnery until I hit the class missions where Elara was incapacitated, I think it was level 30, might have been 40 though.... maybe it depended on who you sent where on that certain mission to end the chapter, anyhow, Elara was down for me for like 5 or 6 levels, and I switched to Combat Medic.. and I like it better, I use 4X as my companion, I completely **** big guys, get 4x buffed, and get my 30 stacks of support cell before we aggro, then I start off with grenades, full auto, and hit super cell, and go nuts with 1.3 sec charged shots, for anywhere from 800 to 2k crits, by the time I run my ammo down to half, the mob is 2/3 dead and 4x is prolly aroudn half or so, I heal him up quickly and easily, then go back with full autpo, etc....
I will tell you, the elites( the guys around 30k health at my level) seem to go down faster than they ever did as gunnery.
I ran out of ammo way too fast as gunnery, now, with supercell, I can spam charged shot at 0 ammo cost, for 10 secs, then at 2 ammo for a while after.
I was all crit/surge gear as gunnery, I am all power/alacrity now, and love being able to squeeze 6 or 7 charged shots in for 0 ammo cost during the supercell buff.