I'm using Backstab over Mutilate.
At first I was appalled by the fact that Mutilate lost its positional requirement. I know I could have kept using it just like before but still I wanted to respec.
First I tried Combat daggers approach and then Subtlety. Turned out it was pretty nice.
Now I'm running my still leveling rogue with this spec:
Talent Calculator - World of Warcraft
Still missing a few points from Precision since I'm not 80 yet.
On Glyph department I'm using Vigor and Backstab, +10 extra energy and 20% more BS damage on incapacitated targets.
My normal rotation on mobs is CS - BS - BS - KS - BS -(BS) - (Evis)
The last two abilities are not often used since the BS after KS usually downs them. Sometimes on clothies / greens I might just do CS - BS - BS - Evis.
Relentless Strikes and Vigor give me enough energy so I can do 2 BS's in a row while regaining my energy while the mobs are stunned so I don't take any hits during the "fight".
Also HaT and Initiative are making sure that I decent amount of combo points. According to Recount addon over half of my BS's crit, giving me extra combo point.
Not saying this is better than Mutilate, just that it's working nicely enough for me since I get no downtime at all. Usually the only time I spend not doing anything is to stay hidden behind my enemy while waiting for my KS cooldown to go below 4s so I can start my rotation again.
Not sure if this will work that well on teams since most of the time I'd be sacrificing my 20% BS damage since the mobs aren't stunned.. either that or spend my combo points on KS instead of some other finisher.
Can't wait to see what happens in few months since I've heard that Mutilate extra poison damage is dropping from 50% to 25%. Also some Blizzard blue poster has said they're reworking Hemorrhage effect to be part of some other rogue skill.
Wouldn't mind if it was Backstab.