Another thought on these lines. If you have 5/5 imp poisons and 2/2 deadly brew, then for 6 seconds after a 5pt envenom, you are running at 70% chance on both hands to apply instant poison. That's some pretty serious poison application.

From Vulajin's Rogue: PvE DPS article

"The best cycle for nearly all Mutilate rogues is 3-5s/5r ..."

I've been using this and most of the time I mutilate at 4 CP when I'm going for a rupture (although I should probably mutilate every time to 5CP, I sometimes hit it anyway). I think it's generally accepted that this is the most widely used Mutilate cycle now, though I could be wrong. Every piece of theorycrafting I have read points to this cycle as the most optimal and I have been getting quite good results myself.
Don't take it from me though. I'd rather read the full (updated) article, if you haven't already.

Ditto to the previous poster, 3-5s/5r is what I run. Here's my typical sequence:

Mutilate (2-4)
<pool energy to 70-80>
Slice and Dice (0-1)
Mutilate (2-4)
Mutilate (4-5)
Rupture (0-1)
Mutilate (2-4)
<Find Weakness fades>
<pool energy to 70-80>
Slice and Dice (0-1)
So on and so forth...

It's important to pool energy before hitting SnD so that you get Find Weakness applied to both the proceeding Mutilates and Rupture. For all practical purposes, pretend that Ruthlessness doesn't exist. It only really serves as extra insurance for a 5-point Rupture in the case that you go 2 Mutilates without a crit.

The only thing that makes this at all difficult to maintain is if you don't proc Relentless Strikes on your SnD finisher, but with proper timing, you can still usually squeeze 2 Mutilates and a Rupture in before Find Weakness fades. The nice thing about this cycle is that 3-5s generally provides you with some slack time on your SnD, so you can still re-pool your energy before the Muti>Muti>Rupture combo without letting SnD drop if you time your SnD just after the energy tick that takes you to 80ish, but before the tick that would cap you out. It just takes a little practice.

I did not end up reading the entirety of this thread, but up to page 15 I did not see anything on the use of elemental grinding stones against bosses with poison/nature immunity. These add, forgive me if I'm wrong on the exact numbers, 14 damage and... 12 crit rating(?) which both are capable of being added to both of the weapons used. Also since white damage for daggers comes more regularly(1.3-1.8) ,depending on the daggers, than swords, the 14 damage increase is highly more useful than on a slower weapon, as well as being increased dps-wise with SnD, as it would be with other weapons of course.

Also, I have not had a ton of experience with end game raiding, mostly Kara, Mag's, Gruul's, but from what I've seen, most all bosses are capable of having a sting on them, which counts as a poison. I will not say that as a fact, as I have only limited play as a hunter, only level 62, so not too much experience with elemental-type bosses.

But, mind you, most all of this is only something to think about. The use of grinding stones is typically what I did in situations where I could not use poisons. that combined with weapon procs of mongoose and other haste granting procs/use effects I got roughly a 9-12 DPS boost off those. It has been a while since I played my rogue as mutilate, so some of this may have changed, but this was how it was when I was Mutilate spec.

I only ever used them on Void Reaver and Hydross. After the patch where they removed most of the immunities from elemental type mobs, I started using poisons on Hydross too since half the time he wasn't immune. That's pretty much the entirety of my Adamantite Sharpening stone usage.

Very true, I was just making mention of it because there are some people that base everything they do off something they read. Had a friend like that for a very short while and he wouldn't budge from what he read. I know it sounds asinine, but I was mainly posting it for the people that are similar to him and get everything they know from others' experience and not their own.

My apologies for posting something so basic as that.

The proc was significantly nerfed in a number of ways (proc rate, dmg of elementals, aggro radius of them wiping groups are the ones I can think of). I got my Shard after 2.4.3, so I can't confirm this, but people tell me they used to hit for 100 and crit for 200. Now they hit for 50 and crit for 100, so they basically cut the damage in half. The roguecraft spreadsheet estimated the proc to add 45dps, so cut that in half and the proc averages out to 22.5dps (overall, not per mob, since this includes times when you have 3-4 of them up at once, I think). However, people have also said the proc rate was nerfed. I can't confirm this personally, again, but if that's the case, then the dps value of the proc overall falls below even 22.5dps. Additionally, it's not fun having the proc aggro another pack of SWP trash. There are definitely some pulls where I'll stop dps'ing 5-10 seconds before the pull is dead to make sure I don't spawn a new ember that goes off and wipes us. This has to do with the change in the embers' level, which is now equal to the iLvl of the weapon, 151. They also see stealthed mobs very easily. This is just an irritation, as it has no effect on boss fights that I've seen, but it is quite annoying. And in a bear run it's worse.

Still.. I wish they'd fix the dagger. They nerfed the DPS of it by at least 22.5dps, making it only marginally better than several other daggers if better at all, and it drops from Illidan, wtf!