Wait...Snipers are...supposed to use cover?
(Lethality Sniper, watching those numbers burn down that HP!)
When I played as a Marksman sniper, I'll admit, if you died to me, you either didn't see me, or didn't care. I would be stationary at some place, shooting at you, and if you didn't LoS me, you really weren't paying attention. If anyone got close, I'd cover-pulse and pray I knocked you away somewhere that you couldn't get to me. If you did, I'd have to pop all my CDs and pray. But, all in all, the damage wasn't really that high.
Then I swapped to Engineering. A bit mobile. Very nice AoE from the 3 second Frag Grenade, and I could defend a turret in Civil War or a door in Voidstar with Plasma Probe quite easily, but despite that, I wasn't killing all that much. Great team utility, very low personal rampage.
And finally, I decided to try Lethality. I have that same utility as Engineering, if a bit more proactive. *Pop a Corrosive Dart on each enemy before you die, and you'll get back there before they can cap.* And, if anything, I feel I do more damage than a Marksman Sniper. Best of all, it's almost all mobile. I barely ever go into cover.
A simple rotation, on someone with full Hp (Tanks and Commandos excluded, reason to come,) goes Corrosive Dart, Weakening Blast, Acid Grenade. One or two Rifle Shots, depending on how many DoT crits I get to give me energy, then Cull to finish it off. They're either dead, or in Takedown range and going down to that. Of all those skills, only Cull requires channeling.
That said, tanks with the high HP stop me, occasionally. Depending on my crits, a healer Sorc may survive long enough for me to have to finish them off with a few rifle shots or a Series of Shots. Most fights, I'll kill the enemy before I'm down to 50%. The harder the fight, the lower I may get, or the more CDs I'll pop. The only ones I lose in a 1v1 fight to are...
Commandos. There are a few really good commandos on my server that I loathe to engage. They've got several pieces of PvP gear, and are heal spec. I have to kill them before they see me, or they'll hold out long enough for someone to show up and kill me.
All in all, I guess, I just have to say, Marksman is a bit of a joke to me. LoS then, burn them down like crazy...There are so many ways that they can be countered that it's not even funny. Lethality, though...You can't counter that. And even if you stun me, all those lovely DoTs will still be ticking. You are already dead, you just don't know it yet.