Firstly; I am just as likely to use my DRK as I am to use my WAR, They literally have the same gear and Itemlevel and I'd like to think that I'm decent at both of them, with PLD slowly climbing it's way to 60 as well...
My oppinion is based upon what I've seen and experienced with the classes, both as MT and OT.
The 20 seconds after you activate Berserk, you'll do roughly 4800 Potency's worth of damage. If there's a melee (We all know that MCH has *The* Burst combo) that can do the same or better in the same amount of time, please prove me wrong and I'll happily cede that claim... Also; Please refrain from calling me a liar.
I'm not even sure what your actual argument here is... A WAR *Has* the best dps of the tank classes. The Raid's priority *is* (after survival) the amount of damage it does to the boss, as virtually all end-game bosses has a enrage mechanic that hits unless you kill it within a given amount of time.
A Raid *will* have two out of the three tank classes. A WAR *is* the best at dpsing, the same way DRK mitigates magic damage and a PLD is unbeatable at taking physical hits.
A DRK's main mitigation skill and resource gain *requires* it to be hit. A PLD's entire shtick is to have Block on top of it's cooldowns to passively mitigate damage and ease the burden on your healers.
A WAR's entire toolset *is* designed around boosting it's own damage and self-heal rather than mitigate damage. Unlike the other two it doesn't need to be MT to utilize it's full skillset, and it's raid-affecting skills both rotate from it's non-enmity combo.
The only instance where another tank class needs to leave tank stance is when a DRK uses Blood Weapon, which it can do and still hold aggro if it's properly timed and you communicate with your raid's DPS and healers. Dark Arts and Powerslash is a wonderful thing when combined.
That you've somehow gotten it into your head that a DRK or PLD in offensive stance is better at dpsing than a Deliverance WAR is beyond me. That you somehow think that higher enmity (which still always caps at "The boss is hitting me") is more important than higher damage confuses me.
A competent tank *will* hold aggro, no matter what class it is.
So yes, it is my honest and sincere oppinion that WAR's greatest benefit to it's Raid group is as a Deliverance-using Offtank that takes advantage of it's skillset to pack as much concentrated dps into it's rotations and cooldowns as it can.
It is my oppinion that a WAR that's MT'ing should rely on Inner Beast rather than Unchained, as it can hold aggro anyway and the 6 seconds of mitigation and the 300 potency self-heal offers more Raid-wide benefits than "Pulling harder on the boss I'm already pulling and holding".