Also, sneaker can choose his targets to kill, he wont surely pick tanks, rather prey on weak, low hp targets.
And that's how it should work. He kills weak targets, like a true assassin, and can't do much against BG tanks(he usually dies, sometimes kills, that's pretty balanced).
You want to nerf Silent Death/sneakers so they won't beat anything?
Now it works kind of like rock-paper-scissors, that's how it should be. Well, actually, BGs with all their anti-crit/toughness features are more powerful than anything else, so there's still no balance.
Please understand, SD bursters
have to be useful. If you nerf sneak so people can see sneakers, they will be trash because invisibility is their only weapon. If there's a group of people fighting and the assassin gets visible, it's his end. In bigger fights he can only eliminate targets that are out of their position, rushing into a group of people is suicide.
The only thing to fix in my opinion is removing the possibility to sneak in front of a person you tagged. Now in 1vs1 fights I can burst my victim and go into sneak instantly(almost), because I tagged him. Doesn't always work so well though, when my BG enemy has the reflex to punish me in the little moment im visible, and he punishes hard.
That would force us to either keep running to a corner to hide, or always try to run to point blank, which is almost impossible when the target is moving.
Conclusion: Don't whine to nerf a feature just because you died. Play in team. There's always a counter to something. Experienced players will find it.
If the feature gets nerfed, it'll probably be rendered useless.