Sorry Havoc your scenario is not "Plausible" at all. As you have one healer responsible for all this damage we can safely assume that it is a 2 healer 10 man and that the other healer is full time on the tank. This gives us a good benchmark for raid damage to compare it to. Specifically the most high raid damage fights currently in the game Saph and Malagos.

In your 10 second window you have 5 people taking 1.666 times their total life pool in 10 second span. Saph is going to put out ~ 2/3 of your hypothetical squishies damage in the same time span. Malagos will do ~ 1.1 times the total life pool in the same span. This is only 2/3 of the individual damage you are throwing at the healers. Here's the kicker though. In both these situations you will have at least a small amount of support from your co-healer.

The only fight that would come even close to this level of healing stress would be KT with melee that totally suck and multiblock each other. In this case the correct conclusion isn't that priests need better healing tools but rather that the raid needs to play better. As others have pointed out there is no example in the game where there is non-avoidable RSTS on the raid even remotely on this scale that has to be healed by a single healer. If you know of one please point it out.

I find the comparison of the trinkets very interesting, and a pleasant departure from the CoH/Pally vs. Priest ramblings that have plagued this thread for the last several pages. Regarding trinkets, and regen stats more broadly, it seems to me based on my experience healing (limited) that the only time I have mana issues and really want regen is when I'm healing like crazy, and therefore subject to the 5 second rule for 90%+ of the fight. In those situations, Int with replenishment is vastly superior to spirit (though I love spirit, don't get me wrong). The most obvious way to get more spirit regen in those situations is to proc IHC more (my gear is a bit lacking there).

With the exception of healers dying, the hardest hit my mana has taken is ranged tanking 4H with a lock and using Binding Heal. With no replenishment, no mana tide/mana spring, the possibility of my Shadowfiend eating a void zone, and me being too proud to call for an Innervate, this is the only fight where I think carefully about how to maximize regen. I'm sure as dps gets more geared, this will be a non-issue too. In the future I can only foresee mana issues with new content or with doing current content with fewer healers.

My gripe with spirit regen is like my gripe with Hymn of Hope. When you desperately need it, you can't take the time to benefit from it, unless you're completely OOM with no other alternatives.

Ghostcrawler has confirmed (MMO-Champion BlueTracker - CoH CD - What will it be and why?) that CoH will be receiving a 6 second cooldown. This does seem to increase the relative value of the discipline spec given the remaining AoE heals are not holy specific and that AoE raid damage may be balanced lower to account for reduced AoE healing.

First, Int is by no means vastly superior to Spirit at 90% FSR. Did some rough calculations and at 1000/1000 and .206 mp5 gain per Int from Replenishment, you gain about 1.5 mp5 by adding 100 Int over adding 100 Spirit (roughly a 10% difference).

Second, the "ramblings" of which you speak are are an attempt at modeling priest performance against other classes in extreme but plausible scenarios. The purpose of coming up with a reasonable model is to determine the potential performance of Holy priests with the proposed CoH CD. If a realistic and representative model is able to be derived from this recent "plague-like" discussion, and the Holy performance is found to actually be significantly below that of other classes (which I don't personally believe it will be, but that's tertiary to my point), then there's the potential for something to actually be done about it before the change goes live and we find ourselves in a situation where Holy has no niche (again, not what I believe will happen, but nevertheless).

So just because the discussion isn't trying to model something relatively simple (i.e. trinkets) please don't try and discount or deter those trying to work proactively to determine the viability of our class.

You're assuming 100% uptime on replenishment though. At the moment I'm running with a 1 SP, 0 retridins and 0 surv. hunters, so I'm definately not on 100% uptime in my 25mans. I'm wondering how many mana replenishers we need in a raid to get 100% uptime. Two, maybe even three? Anyone have some idea?

Furthermore I'm more interested in an int/spi vs spell power comparison. Int and spirit aren't that hard to compare against each other. Spell power on the other hand, is a lot more difficult to compare. I haven't found a lot on this topic in your startpost, unfortunately. It's a great writeup nonetheless though, thumbs up. Lastly, I don't see Flask of the Frost Wyrm in the list of possible flasks, any reason for that?

With the 6s cd to CoH on it's way, it may be valid for holy priests to ignore regen and haste as much as possible. CoH will still do the most healing per mana in a raid-healing situation, but we can only cast it once every 6 seconds. Rather than waste your mana on inefficient heals during the cd, stack crit and spell power (at the expense of haste/regen) and make CoH hit as hard as possible. CoH, SoL fheal, PoM might be the only spells worth casting and it will be hard to go oom w/ that rotation.

Dude, you can't be serious. No offense, but... this is like ... the stupidest thing i've ever heard. This is not even about "what blizzard wants the classes to be"... it's about how the player plays his character in every possible way. To use the full bandwidth his class has to offer, and not "spam this... use that and mayyyybe keep this on cooldown". It's a shame what some people make of this awesome class.
Go play pingpong if you want something easy and cozy.

Sorry for this "outburst" ... but sweet dancing jehova, Priests aren't frickin' "spam one heal"-Machines!!!!!!

In 10/25 man raids, CoH accounts for the majority of our healing. Adding a 6 sec. CD will no doubt change how much CoH is used in comparison to our other spells. Spamming CoH means your spending very little time if any OO5SR, thus a Priest in that scenario benefits more from mana regen mechanics like MP5, replenishment, etc.

However I don't see the need for a significant change. I would have to disagree with "it may be valid for holy priests to ignore regen and haste as much as possible". I would be wise to utilize the time between your CoH CD, as opposed to try to compensate for it by stacking crazy amounts of spell power/crit.

As long as they use their abilities that trigger Replenishment once every 15 seconds (easy for Judge and MB), and assuming at least 5 characters in the raid that don't use mana (warrior, rogue, feral druid, death knight), you need two to have a nigh 100% uptime. Three to make sure, or if you have a lot of mana bars in your raid. A well stacked raid includes at least two Replenishers for a 25 man, in my humble opinion.

Also, int/spi and sp comparisons are somewhat silly. One is longevity, the other is throughput. As has been said before in the thread, it's apples to oranges in comparisons. Both need to be balanced appropriately, but it's hard to give an exact "worth comparison" outside of benchmarks.

Results will vary (and generally favor intellect more) depending on how many factors you include. Besides replenishment, IHC and shadowfiend also increase your Mp5 due to intellect significantly, as described in section XI b of the original post.

Also, there are some formulas related to the value of int and spirit posted here. From those I get a 21 mp5 advantage of int over spirit -- still small, but in the opposite direction. Those computations are for a holy priest and account for replenishment, IHC, blessing of kings. In addition, according to the "Spirit Threshold for Holy" graph, at 2200 combined int and spirit, you're better off with more int than spirit (for mp5).

Maybe it's a dumb question, but why isn't Replenishment + Shadowfiend + Mana Pool Size + Mana Tide counted in the spirit equation, as you do it with the Int?