When I dps I am offended when I'm guarded. Makes me think I don't know my class or role.
So a PT doesn't know his role when he pulls aggro?
Thanks to bw one of the top burst dps classes doesn't have an aggro reduce.
If the two dps are equally geared, I will guard the PT because of that fact.
As a Shadow tank, I have yet to find a situation where extra endurance/health does me no good. Since I'm not in the business of losing aggro, it helps to provide the healer with a bit more leeway.
When the extra health goes on cost of shield/absorb/defense (before you hit the wished caps, I don't know what they are for the assa/shadow) then it's doesn't help the healer.