I'd love to see silent death made useful somehow. Maybe changed...
It'll be useful if it'll work for any weapon if:
1) In real time only if you weren't in combat mode, so your first strike/shot(from 1-3 hexes) from behind will cause x2 damage, regardless of in sneak mode or not in sneak mode, your 1st attack from behind will always cause x2 damage, untill you will go out of combat mode again.
2) In turn based it'll cause x2 damage only if you strike/shoot(from 1-3 hexes) from behind while you were in sneak mode, again regardless you were seen or not, all you need is just to be in sneak mode (you can't reenter sneak in TB anyway after that, even if you'll hide), so it'll be again only for your 1st attack, and only if your victim is looking in opposite direction from you.
Requirements same as now.
So if you want to be SG/BG-burster in quarters playing kamikaze quake style or ambusher or you can simply ran to victim's back and burst, if you wasn't in combat mode (someone didn't shoot you while you were running to the victim), you'll deal x2 damage.
But to take this trait you'll need to spend points into unarmed and sneak, even if you're BG/SG-burster.
Or.. make it only for unarmed/melee, but then x2 damage will be useless, better give additional critical% and critical roll which will stack with better criticals, so you may make good critical roll and knock out target from behind if you made critical strike.
Adrenaline rush can be used as Psycho drug when your HP below 50%.
Quick recovery should give you also immunity or some kind of roll against knock backs from grenades and melee attacks.
You also forgot about quick pockets! Which should allow to you to move items from slots without using APs at all, so picking up droped weapon will consume only picking APs, while moving it from inventory to hand slot will consume nothing.