Are my mitigation numbers off ?

[Giantbane]

For casual stuff like Titan, yes you're right that the core problem was basically just that IB depleted your Wrath so you lost the healing buff, which was a stupid design decision, but it was pretty much doable with reasonably similar gear.

PLD were MTing it in i50-i60 gear since they'd have cooldowns ready for most of the tank busters and constant blocks. That was a more difficult feat to pull of with the WAR.

Yes, and it would be far more risky that the other two tank...
Less defensive, more offensive...I don't see a problem here.

It's a balancing headache because you've got surviability and DPS intertwined, but only for one job. The other two jobs would scale separately.

You'd end up with either the DRK too good or the DRK not good enough and would be very difficult to find a middle ground.