Some notes on what I've observed in Mount Hyjal and BT...
Anetheron -
We're great tanks for the infernal adds due to Exorcism/Avenger's Shield (they're taunt immune, sadly). We tank the infernals away from the raid so being able to provide your own FR aura is rather nice.
Azgalor -
Again, we're great add tanks here. The Doomguards are easily picked up by Exorcism/Avenger's Shield/Righteous Defense, and since there's usually not a whole lot of DPS assigned to them, the damage output of a tankadin helps a great deal in comparison to a protection warrior.
Archimonde -
With the Fear Ward changes, I think this has become more tankadin-friendly.
Naj'entus -
Tankadin threat generation makes this fight a lot easier. The only thing that really held us back from it was the stamina curve, and post-2.3 it should be a non-issue.
Supremus -
Being able to pick him up from range after a volcano phase is priceless. Also, increased threat on this fight is never a bad thing. <3 demon bosses.
Shade of Akama -
With the hallway adds coming in groups of three, this was almost made for Avenger's Shield. A tankadin can easily one-man tank one of the hallways, allowing DPS to burn down the incoming adds faster and reducing the chance of screwups.
Teron Gorefiend -
Doable but slightly risky pre-2.3, this fight now becomes even better with our increased stamina. Being an undead boss, this allows a faster DPS race (always nice when you have party members being lost to forced death effects), and his ability to drop large crushing blows favors us as well.
Gurtogg Bloodboil -
The tankadin's ability to micromanage threat makes them an ideal choice for what is a very threat-sensitive encounter due to the need to force tank transitions. We also have the ability to completely clear a stack of Acidic Wounds, which neither of the other tanking classes can do. We can also throw out a few heals when offtanking (which is nice if you're stuck with Acidic Wounds and bubble on cooldown).
Reliquary of Souls -
Due to our blocking mechanic, tankadins take far less damage in Phase 1 (Essence of Suffering) than protection warriors. While some guilds choose to use multiple party members to "tank" in Phase 1, the fewer people you have to worry about, the better. I agree that Phase 2 is still not optimal unless you have absolutely insane DPS (our guild is fairly new to it, but we can only miss 1-2 Deaden reflects without getting screwed). That being said, tossing on a Nightfall with SotC on helps with DPS (and for those guilds not using Ret Pets, imp JotC would be nice as well). Phase 3 however, while there is very little actual data (non-theorycrafted) out there, appears to be very tankadin friendly. It's great to hear your healers say that you're EASIER to heal than the warrior tank for a change
Oh, and since there was no entry for this (how?)...
Doom Lord Kazzak -
Being able to kill this guy before Enrage (or midway through the first Enrage) is priceless, but the amount of threat required to do so is our forte. Positioning him quickly is a little hairy assuming you're pulling with AS, but it's a short learning curve

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