Yeah.. even with the best possible scenario (509 ilvl weapon) it only takes 103.5k to make BB do more single target damage, making heart strike pretty much pointless.
You technically should be watching your AP to see where you're at while not taking much damage (such as a tank swap) in order to maximize dps, but this is maximizing your damage in a time when you will be doing diddly squat for damage anyway since if you had vengeance enough to do decent damage you would probably be using Blood Boil.