It doesn't require math though. If you're causing your healers to run out of mana, either they have to be more efficient or you have to gem avoidance to take less damage. Extra health will only buy some extra time for the healer react, not make them use less heals or more efficient ones. The complicated math part would be whether you should gem dodge or parry which behave very differently in Cataclysm.
Originally Posted by Fledern
If avoidance doesn't matter come Cataclysm then I don't see how mana will matter either.
"Just because it's not nice doesn't mean it's not miraculous." - T. P.