Just get both and swap based on the fight.
Based on the fact that on PTR they only changed the tank cloak to specify the spec, let's hope for now that it's only to avoid cheezing mechanics (H Primo dark blobs exploding)
Or being a free extra soaker for a mechanic. It would come at a cost for intellect users (casters/healers), but any agi or strength DPS can easily reforge the tank stats and gain a cheat death, which would be... quite nice. Stuff like DPS DK's taking it to live through Static Shock for instance.
So with expertise replacing dodge this seems to make this cloak suited well for progression doesn't it?
Not really. It's a step in the right direction, but still:
1) no native haste
2) very situational and likely unused proc
3) loss of the DPS cloak proc, which now scales with AP (WTF OP)
Unless they nerf the DPS cloak (or balance encounters/tank damage around the assumption that every tank has the legendary cape), most any progress minded tank will take the DPS cloak.
Further stacking mastery just seems like wasting stats, given that we'll be pretty damn smooth at that point.
Crit does have a benefit in throughput, but does fuckall for survival (for what that's worth).
Avoidance has minimal throughput on ST, but HUGE boost to MT fights, which is my big selling point, for now.