Except there'd never be a case where you'd be in Aspect of the Turtle for any sustained period of time. You'd use it as a personal CD during big raid wide damage burst, and that's it. If you're in bleeding edge progression where there is constant, sustained raid-wide damage in large amounts, you'd still be in Hawk because when the choice comes down to "DPS the boss harder so he lives less time and let the healers heal through the damage" vs. "be less hard to heal but keep the boss alive longer" the former will always win, not only for you, but also (and this is the important part) for healers too, in terms of healing needed.