I think Stalkers are going to be a troubled AT, simply because they live or die by their ability to hide. Hide is one of those all or nothing kind of powers, like SR is for scrappers. If they can never be seen till they attack, they really are too powerful for PvP purposes, as they can 1 shot kill pretty much everything but tanks. The whole balance thing goes out the window there. On the flip side, if anybody can see them with just a +perception power, then they are dead where they stand. Again, the balance doesn't exist.
Perhaps a good solution would be for the +perception powers like Tactics to give a percentage chance of seeing a stealthed character, rather than a straight visual. It could be a pulse like power that rechecks every 2 seconds or so, so that even if you see them now, 2 seconds later you lose them again and have to hope you dont get assassinated if you choose to stick around.
I don't see an easy fix for this otherwise.
