Evi or Env for Mutilate?Follow

Having recently hit 80 I'm going to start doing some heroics and eventually raiding.
I levelled mutilate and decided to stick with it and spec mutilate raiding 51/13/7

http://www.wowhead.com/?talent=f0ef0exoVboIzAo0xV0hZxb

I never used envenom in the past and wondering whether I should change.
If I got rid of Imp. Poisons for Imp. Evi and put the 2 points somewhere else and then couple this with the Evi glyph.
On trash mobs I never usually rupture so would evi + wound/wound would be more effective than stacking deadly and env?
It just seems a waste on trash mobs stacking the poison, on bosses however I persume would be a different matter.

Is there any equations/tests that show the different in damage (which I can only see being on boss fights)
Does anyone use evi over env, and why?

There's room in a raiding mutilate build for 5/5 imp poisons, and should be fully abused as such.

If your weapons are both < 1.5 speed, just stick with instant/deadly for both trash and bosses. There's nothing quite like chaining 7k envenom crits/5k mute crits on trash. If you're lucky enough with ruthlessness procs you can keep the envenom buff up almost constantly on short trash fights =D

When glyphed for, you would drop 1 point into Vigor and go 4/5 Imp Poisons for raiding. But there are some arguments back and forth about that. Otherwise 5/5 IP is basic raiding setup for mutilate.

For mutilate, deadly goes on the slower of your weapons. IP or WP on the faster. I often run WP on trash but with all the AOE going on I'm not sure it matters much right now. This may change.

currently i have 1pt in vigor and 5/5 imp poisons, do you guys swap that 1pt in poisons and put it into ruthlessness?

Just been running a few heroics and I tend to find wound/wound on trash works fine with evi, and deadly/instant with env on bosses.
Trash mobs don't allow enough time to stack deadly and I find my evi crits hitting harder.
With this rotation for trash:
Garrote
SnD
Mut x2
Evi

And for bosses:
Garrote
Mut x2
Snd
Mut x2
Rup
Mut x2
Env

Refreshing HfB when below 10 seconds.

I'm glyphed rupture, snd and garrote but not sure whether to drop one for vigor, and lose a point in imp. poisons.
I'll have to look into it.

Taking 1 point from Ruthlessness would be worse than taking it from Imp Poisons on my spreadsheet, so... dunno.

here's what i dont get: sure envenom isnt affected by armor, but what about the deadly poisons it consumes? do the ticks on them get added to the damage of envenom, or are they just lost? also, doesnt that potentially lower your dps because then you have to wait for a poison to be reapplied before you can mutilate again?