We were not talking about heroic modes, we were talking about entering for the first time in MV.
You said it yourself: you gem spirit because you get more from it and not because it's a better stat. I already said that in my post below the one you quoted.
Well, as I said in the post above spirit is not that good at the end of the day, imho, 5k more spirit how much will give you in a 7m fight? 7-8 more healing rain? And you trade it for what? You have to take into account all the factor, not just the spirit you gained.
If you go oom in the middle of the fight you have to analyze WHY your mana reached 0 so fast and not just think "Oh crap, I'm oom, I need more spirit".
I explained what I meant with "cap" and you are saying basically the same thing. You reach the cap when you are confortable with mana ergo when you end the most healing demanding fight over the 6 with at least 20% mana left. Then we can talk hours about RNG and stuff like that, shit can happen everytime so it's up to you how to determine how much mana left is confortable for you.
Good point. As you progress and get some boss in farm and after few nerfs even 2 healers will be too much tho. We are talking about "normal" set-up that usually requires 3 healers. If a fight is intended for 2 healers (gara'jal for example) the damage incoming is designen to fit this set-up.
The problem is when 3 healers are much but 2 healers are not enough. What you will do?
But I see we are saying the same thing: you have to balance mastery and crit, according to your raid composition, to the fight, to your heal style and w/e.