Wouldn't you say something like "A good rule of thumb is that if DPS Warrior * 2 plus non-Mutilate Rogues is greater than or equal to 3, Windfury will provide conclusively better DPS regardless of the rest of the group's composition."? (Could also be re-written as "greater than 2", if you like.) I think this is agreed on as true by most of the reputable theorycrafters and it also is more specific (for example, I sometimes drop GoA when I'm running Karazhan with a feral tank/undergeared Warriors in the group to push off more crushes: I'm well aware it's not the best DPS, but it's still "better".)
Well, there are better options than the Gladiator weapons available in BT (e.g. Rising Tide); also, if we're trying to eliminate extra posts or just having the option to linking people to the sticky I'd maybe split up these points, just so that people see it when skimming quickly:
- Windfury Weapon (the self enchant) has a 3 second cooldown incurred each time it procs, regardless of which hand procs; it has a scaling proc rate from 16% to 36% on each weapon strike (((I don't remember what the exact conclusion was on this, but seem to remember something like this from Disquette))). Even though this cooldown can no longer be bypassed by downranking the offhand, max rank Windfury Weapon remains the best-DPS enchant for use on both hands, primarily because it scales with Enhancement gear while other enchants do not.
- Slow weapons are preferable to fast weapons for use in both hands due to the Windfury cooldown. Currently, all weapons which have a flurried and hasted speed below 1.5 seconds (i.e. those with a listed speed of less than 2.0) are inferior to even high-level greens for DPS. The best easily-obtainable options are the 2.6 speed Gladiator weapons in each hand.

I need to clarify my original post, Rob is correct in that I should have said greater than two, or greater than or equal to three but I am trying to avoid getting bogged down too much in details so I may leave the latter part off. The line is blurry enough depending on the level of gear and specifics of what the warrior and rogues are using that I am going to say it's just better for the warrior because of execute. I have a few more edits to do via PM and I will re-check the Bloodlust thing again tonight (I have access to a mage).

Updated with some clarifications and additional notes. Thanks to the people contributing to this thread.

400mana/5 means you can dark pact for 1.6 k mana every 20 seconds. Considering the average casting sequence of Ua/corr/immo/coa/siphon/sb spam/refresh lasts about 18 seconds, it means that you can dark pact once every rotation.

As for the assumption that every raiding affliction warlock should have Imp. Lifetap, I strongly disagree. If you're deep affliction, you rely on dark pact, NOT on lifetap to get mana back. Lifetapping means you require healing/lose gcds using pots. As far as I'm concerned, lifetap just wastes gcd's and time that can be spent recasting dots, and I believe affliction locks only use it when they absolutely need mana that dark pacting can't provide at that particular moment. So putting 2 talent points in a talent used rarely is a bit wasteful, at least for dark pacting warlocks.