As I said before, don't base your choice on the current nerfs. Things change all the time in MMORPGs. I mean, the first nerf came in the first month of the game. But they will balance things out for sure (probably disadvantaging other classes in the process, maybe nerfing some, then having to balance them out again), but that's the way it goes.
Don't go for the FOTM choice, that's all.
Besides, if you already have a gunslinger, it's the sniper's mirror, so you'd play the same class in terms of abilities (just with different names and looks). You could try the operative, see how it goes, get used to the stealth, maybe go stabby and pick concealment or the healer way and go medic. Try it out for a couple of days, see how it goes and if you really hate it, go sniper.