@Freia: About our raiding format, we do 10m and just tonight we first killed Jin'rokh hc. We 3 heal almost the entire raid. I've read that some bosses can be 2 healed, with the obvious DPS improve, but we haven't tried it.
@Xs: I know that if I HR like a mad I'll OOM in nothing, but my experience in ToT says me that is very very unlikely we find that HR spam scenario... may I be wrong and in some hc's I must do that? tell me please if that situation is possible and I'll understand your post :S
two minutes HR'ing in a boss fight? tell me where and when, master-of-challenging-content!!
Not always a good idea to come asking for help and follow it up with name-calling. Those situations are highly likely. I don't anymore, but I used to heal heroic 25 mans and once you get to bosses nearing the end of progression it gets quite hectic and demanding for most if not all of the fight. You'll hit fights that you have as many people as dps (thus less healers than "normal") and it can require a lot from you.
Long story short, healing isn't something that really had a definite answer like any dps class. If you would feel more comfortable with less spirit and more "healing" stats then do it. But if you start pushing harder content you'll realize you'll need that holy radiance more and more spirit.
My first post on MMO forums. Figure I'll try to give my 2 cents about regen vs. Throughput.
Ideally, you are supposed to end a fight with 0% mana, (almost impossible, but like I said, *ideal*)
You can look at people like Bobina, and Noddz from Blood Legion, arguably 2 of the best Holy Paladin healers in the world, and see that they know no amount of spirit that can become less useful than output stats like int or haste/mastery.
I look at it like this:
+100 Int = stronger heals
+100 spirit (across a boss fight) = 1 - 2 more heals.
If you are ending a progression fight with 50% mana, that means you can afford to heal more; be a little more reckless, throw a few more saves to keep people out of danger (FoL), maybe throw some Denounces. That said, Holy Paladins are fortunately equipped with a Mastery that actively reduces the negative effects of Overhealing as our gear gets better, so avoiding the act of overhealing like the plague isn't really necessary.
Sometimes, if I find myself having a lot of mana at a good time, and I've planned DP, Pot, and Arcane Torrent well, I will just stack IH shields with HR, Daybreak, LoD and Holy Prism/Light's Hammer, so the raid avoids some damage if I can predict it coming. A few examples:
Rain of Blades, Unseen Strike, Dissonance Fields, all in HoF. Expel Corruption, Get Away in ToES.
Quills, Gas on Primordius, Interrupting Jolt, Iron Qon Fire spears, and Head Smash, TC Waves during Dusk phase, Thunderstruck and Gale on Lei Shen, all apart of Normal ToT.
All that said, as a Holy Paldin in MoP, IH benefits healing whether its needed RIGHT NOW or not. I'm not saying that shield stacking is the way you should spend your mana bar, but I think the better option between A. Losing a bunch of spirit to gain more powerful healing, or B. keeping spirit and throwing more heals quantity wise, is definitely B.