TBH I thought you were crazy when you said that high stat gear was BiS because I have always been under the assumption that High end gear with stat augs was the way to go. That way you get a healthy balance between health and mitigation, but I've noticed while getting my 72's I've been trading defense for Abs and health and it makes me feel real squishy. I might actually pick up the high stat mantra (maybe if i get around to regearing). But i do have to say that if i didn't have all this hp terminate would 1 shot me 100% of the time unless i had a CD running, and thrasher could probably 2-3 shot depending on unlucky rng with those 15k swipes.
I think having a skill like you said that turns giant hits into dots would be amazing, like any attack over Xk damage is turned into a dot. That shouldn't be hard to balance because you really aren't adding to their defensive ability, just making them a little smoother on the healing stage