I'm playing Mutilate since almost 2,5 years, that's why I surely can state of mine, that I've made a LOT of experience with Mutilate in PvE (casually, but if, then BT) and PvP (Realmpool 1st s4 shoulders with Mutilate, best PvP rogue of alliance, 3rd on server)
Your 80 PvP build just sucks. Neither FA nor Ruthlessness is specced - absolute fail. But instead of those very necessary talents, you specced Imp. KS, which just can be resisted, parried and dodged (ok, parried and dodged should never occur but still possible in times of latency
). Moreover, Eviscerate will just be used on enemies below 20% health to put an end of the match, but 21% more damage with just one ability isn't worth 3 points.
In my eyes,
http://www.wowhead.com/?talent=f0eco...GzZ0xZebfbh0db
is much more useful. In spite of the upcoming HfB buff (it's just confirmed, that there WILL be a change, but not known in which way), this could be an alternative:
http://www.wowhead.com/?talent=f0ecReMoiroIuho0xZxdbbh
The point in SoH can ofc be also put in MoD or Camouflage, but 1/3 MoD isn't really useful, Camouflage doens't stack (ok, 2 sec lowered stealth cd......)
Now about the poisons....it's just the other way round you should use the poisons:
Mind-numbing on MH, Wound Poison on OH. Mind-numbing will procc much more often, feding up Pallys and Priests. With 2/2 Deadly Brew it also will slow the enemy, exactly as Shiv does with Wound Poison. Moreover, Shiv can be used as an MS (!) and the Shiv damage is raised a little through the dmg of Wound Poison.
Slow daggers are ofc recommended.