Well if you haven't chosen yet I'd say go with the gunslinger. People seem to have the idea that being rooted as sharpshooter is your only option. Personally, I think cover is an interesting concept and is just a different play style. I respec'd my sharpshooter to a saboteur/dirty fighting build and I do decent damage, have great energy management (courtesy sabotage), decent defense (courtesy sabotage), and unlimited mobility. I'm not confined to cover and because my slinger doesn't have the flashy animations that come with the high tier abilities, I'm rarely targeted and I'm free to run around and devastate. There are options other than staying still and aiming a shot!
Although its nice to be able to respec to healer, let's face it, you're a gunslinger for one reason: devastation with flare.