a health bar isn't the only thing that a Tank brings to the table...

Pallies don't even stack stam, their HP has traditionally been lower than other tanks. Warriors shouldn't be stacking stam either...
The only reason why druids are favored as MT for 3D is because of the sheer volume of AOE damage. DKs have mitigating mechanics that allow them to avoid much of the damage, and druids are the only guys physically capable of soaking it.

This doesn't imply that a palli or a warrior is inferior. In most other fights, a palli would be preferable over other options due to their consistent mitigation. Pallies are easy to heal (when geared properly) compared to a stam stacking bare.
I really should roll a warrior... I can't speak authoritatively on their mechanic... but I believe it is something similar to a pallies (tank wise). Their damage intake should be a bit more spikey than a pallies, but the overall mitigation should be equivalent.
Granted that DKs win the DPS game, and bares (as kitty cats) will come in second, but we'll put pallies at a close third (mine pulls 1700 on patchwerk). I am bothered that warriors are stragglers in this... but Warriors are better vs casters than pallies (spell reflect) and have much more buttons to play with while they are tanking.

You can't argue "Tank Equivalence" based on a single fight. That fight is a raid stack hardcore challenge... it is not your run of the mill scenario. In 3D, who do you have tanking the adds? I betcha that a warrior or pally might be found standing there.

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To solve your personal tanking problems, i suggest you try stacking mitigation instead of trying to compete with bares on big bars. You want more threat? Stack shield block... nothing pisses off mobs more than hitting them with your board. You want to live longer, put that board between yourself and the big baddie.
Deal with the fact that you can't soak a fully buffed Sarth breath... neither can I... Thats why we have an entire raid there to throw in the assist... Warriors and Pallies have MT'd 3D.