Haste will allow you to have more renews up on more people by lowering the GCD, but its not going to make it tick faster. Spellpower is going to give the most throughput bonus, assuming you aren't overhealing.

Personally, I've found just the opposite to be true. Prior to entering phase 3, I tend to renew the group I'm not in, holy nova to keep my group up, flash the people with debuffs, PoM people who dip low, PoH if I fall behind, and CoH on cool down. Holy just has so many tools for different situations, I personally prefer it over disc healing in phase 3.

I've tried healing as Holy on 10 man Anub Hard and it usually extends the fight longer than when i was disc. Extending the fight is a big no no as the adds will eventually insta gib the add tank. This is an instance where higher HPS doesn't do the raid much good, since the lower the health of the group, the faster the fight goes. And remember for those who discount disc, do they have a pally using BoSanc? The 3% damage reduction is nothing to sneeze at, especially for large raid damage fights.

That said, it is gratifying to me to hear that people are able to use each spec nearly equally effectively.

I have dual specced into holy, but find fewer and fewer fights to use it on. I suspect this may have more to do with raid make-up than any shortcomings of the spec itself. We usually run 2 Resto druids (in 25s), and adding a 3rd hot class just results in someone's heals not being effective. I think any discussion on specs and appropriateness for fights has to depend on the raid makeup. I find it a bit ironic that i do much better as disc on NR Beasts Hard mode (25) than when i was holy.

Drawing conclusions from Anub-10 don't mean a lot since the fight is a lot easier than the 25 version. I don't see anyone going holy on the 25, since all the nice AoE healing of holy is worthless there.
As with any case it is dependent on healing setup etc.

Recount guessed absorbs isn't "not the best" for this fight. It's worthless. Every time you absorb a light/dark pulse while under the effect of PW:S it's counted as PW:S 'healing'.

For a quick sanity check, multiply the number of glyph of PW:S heals by your typical shield amount (8k) and see if they're remotely close.

Your 2.5 million absorbs done would correspond to 312 shields cast during the fight. Your maximum number of PW:S casts with a 6 minute enrage is 360.

You misunderstand. On a fight like Twin Valkyr, the mitigation of your shields can be treated effectively as raw HPS. Your shields are consumed almost as soon as they're cast, so so the "health buffer" factor of PWS spam (which is so valuable on spike damage fights like Northrend Beasts or Jarraxus) is all but meaningless on Twin Valkyr.

You're competing directly with Holy (and Resto Druids / Shaman) on your HPS output potential, and it's improbable that you'll win. Unfortunately logging tools are all but worthless on this fight, so it's impossible for anyone to provide logs as hard evidence either way. We can only look at the spells available to each spec and rely on theorycraft.

That's not to say that Disc is worthless; the 3% mitigation is excellent for raids with no Prot Paladin, and depending on your strat Disc can perform well as spike damage healers for orb soakers.

Edit: And to be fair, it's not like there's some massive 200% gap between Disc and Holy. If you're more comfortable with bubble-spam and it's working for you, then by all means stick with it.

I see what you're saying. No we do not have a prot pally, so I bring that utility. It just seems to me that 3 holy priests, resto shammy, and a resto druid would be over kill. It may also be that healing isn't as tough as it should be, since my guild is insisting on cheesing the encounter.

I've done Twin Valkyrs as both holy and discipline, and my impression is that holy just flat out has more throughput given the spells you want to cast. The ideal healing setup is probably 1 paladin, 1 druid, 1 shaman, 1 discipline priest, 3 holy priest. Use a druid and three priests to soak and give the fourth priest a holy nova group. Of course, the fight isn't THAT hard. There's a lot of raid makeups that work. We've done 3x Discipline priests on the fight for the last two weeks, largely because it didn't seem worth the trouble to respec holy and then back to discipline for Anub'arak.

I highly agree with graigh, the disc priest provides that "buffer" so that others may get to the one needing of heals. I don't agree on having 3 disc priests tho, isn't that a little redundant?

I am trying to get a sense of whether or not i am performing well enough as holy.

I almost exclusively run disc, which isn't a problem since we have an abundance of trees healing in the raid. However, I do need to learn how to heal as holy since there are occasions where having the healer flexibility is more important than the dps flexibility.

Anyhow, so last night on our first kill of 25 man Heroic Twins, i was holy for about 65% of the attempts (and the kill).

I can't help but notice the absolutely gaudy numbers the druids are putting up, (9-11k HPS on WoLs), while my own numbers were about in the range of 6.8k-7k HPS. PoMs were about 40+% of my heals, then CoH for 20%, then Holy Nova for about 15% and the rest were renews, etc. My holy spec is not a maxed out raid healing spec, and my gear set is still more suited for disc than holy. But I wasn't clear on whether I should have been hitting Druid numbers or not. We 6 healed our kill, though our pally died about 70% in.

I don't have time to cast nearly anything but CoH, PoMs, and HNs, in fact I know my renews were low since they seem to be a waste of GCDs when the raid damage was really pouring out.

While I know there is room for improvement, i am trying to get a sense of whether or not i am in the right ballpark.

Regardless, around 7k effective hps sounds right to me for twins. I wouldn't expect to be able to compete with druids in terms of raw hps on a fight were rejuvenation/wg works so well. I don't really think the log would tell us that much.