Further, holding aggro is a non factor, seriously baffles me when tanks don't make use of their aggro toggles lol like if you have aggro issues now you shouldn't be tanking at all.
Staying alive is covered by CD management. HP values are what healers concern themselves with and judge when you need a heal and when you're fine without a heal, not you. Sure, if you have oGCD stuff like Equilibrium or Aurora why not, but wasting GCDs on healing is pointless unless it's ACTUALLY needed.