I don't want to enter into the discussion itself. But to say that the EH vs. avoidance-question was answerd in Wrath so it can be dismissed in Cata is much more ignorant than to ask the question again in Cata. That's because things have chaged in Cata and they have changed dramatically in many regards. One of the core assumptions of the wrath EH-favoritism was that healer mana just does not matter. And that's definitly not the case in Cata. In Wrath there was no danger of healers going oom so focussing on EH to prevent 3 shotting tanks instead of avoiding dmg was a no brainer. (Well not a no brainer, because if that would have been the case there would not even been such a discussion.)
Now healer mana matters much more and spike dmg is much more predictable than in Wrath. So it's a valid question to ask if that changes anything. EH is about beeing able to deal with worst cases of rdm numbers. If we have to deal with final mana, it's also a good thing to ask about the probability of the worst case happening. If this probability is quite low it may be better to wipe once because of this worst case instead of not being able to beat the boss at all with healers going oom.
So as long as there is a good chance that healers go oom the more important question is how to prevent healers going oom. You cannot answer that question without knowing what our healers do and how incoming dmg patterns are. I don't know enough to answer this (my healer is only 83 and I have only been inside a new raid with my tank at one evening).
Another thing to consider is the input we can make to our EH. Our base health is quite high at the moment. We cannot change armor and have only few options to boost our stamina. EH is about being able to survive another hit. If you cannot change much in this regard it's not much of a discussion anyway.
Something that has changed is that most tanks don't gem for stam only. If you don't take set bonuses you throw away some of the stats you could have on your gear that may help your healer.