One of the intended changes implemented in 3.0.8 was the introduction of a 6 second cooldown in Circle of Healing (CoH). While the topic of whether or not this nerf was justified when talking about a Holy Priest's role and function is completely overplayed, the bottom line is that the change is in and we have to deal with it.
A couple of nights ago, I ran some Naxx25 with the guild while specced CoH Holy and had a very different experience than I normally do. To highlight the differences, let me first pain a picture of my previous healing experience in a 25 man raid environment as CoH Holy.
Pre 3.0.8, a.k.a. EZ Street
Before Tuesday, raid healing for me primarily consisted of bouncing Prayer of Mending (PRoM), Flash Healing here and there, and firing off a CoH or two. Raid statistics generally saw my healing as an equal usage of PRoM, Flash of Light and CoH with Renew at a distant second. As a point of note, Flash Heal usage was often a result of Surge of Light procs. In fact, due to my reasonable Holy Crit rate (>20% base Holy Crit) in combination with the Glyph of CoH, I would often be surprised if I didn't get a Surge of Light proc after a couple of CoHs. Our strategy for burst healing in situations where more than two people were taking damage was to CoH two to three times and then use the Surge proc to instant Flash Heal the person needing the most healing. Most of the time, I gamed the Five Second Rule (5SR) with Surge procs to maximize our regen. Actual CoH spam, where a Priest only used CoH and eschewed usage of other healing spells wasn't common unless the raid was in a very dire situation.
They key point here is that due to Surge of Light procs and the relative efficiency of two to three CoHs chained together to keep the overall raid health in the green, I often had ample opportunity to sit back and regen mana. Very few fights saw me popping Shadowfiend. Incredibly rare situations called for both Fiend and a Mana Potion.
Post 3.0.8 Observations
After this Tuesday's patch, raid healing during my Naxx25 guild run became a much more frenetic responsibility where the downtime created by the six second CoH cooldown was being filled by harried applications of instant casts and Flash Heals. I found myself having to anticipate damage by applying Renews and bubbles on people who were liable to take splash damage, Flash Healing people who had taken significant damage and popping CoH and PRoM at nearly every cooldown to hopefully proc Surge of Light, which could then be saved to possibly counter burst damage.
They key point here is that due to decrease in quick applying and sustained raid healing, it took the healing crew longer to top everyone off to a safe level. This increase in time spent healing resulted in a decrease in time spent out of the 5SR, thus limiting regen and putting a strain on my mana pool. At various points in the run, I found myself focused more on the raid frames, playing whack-a-mole with Flash Heal and Renew, than on the environment. This usually results in a dangerous situation, as not recognizing a bad situation because having healing tunnel vision often results in one's untimely death. No, I didn't stand in the fire, but I almost missed a Thaddius Polarity Shift.
I believe that the biggest adaptation isn't going to come from the healing crew, but from the Raid members understanding that raid healing just got much more time consuming. Not panicking and watching one's own back with a finger on the Healthstone, Health Potion, or defensive cooldown may be appropriately prudent.
From the healing crew perspective, an adaptation that should be realized, is that the notion that 'everyone needs to be constantly topped off as soon as they take damage' will not be possible anymore aside from some extreme raid stacking. In correlation with that, healers should begin to realize that it's okay to let a Renew/Lifebloom tick to full to top someone off if that target isn't in mortal peril.
I found it very helpful that Grid, my raid frame mod, displayed incoming heals so that my single target spot heals were not overlapping (and thus overhealing) someone else's heals. However, the best part was that due to my configuration of Grid, I could see who had Renew, Rejuv, or Lifebloom already on them. This would consequently save me some mana as I would let them tick to full instead of spot healing, and nab myself a GCD or two of mana regen.
I realize that CoH was grossly overpowered. It was. There's no argument. However, the healing playstyle of a Holy Priest was far more fun with a spammable cross party AoE heal. I enjoyed it because of its ability to put out some incredible raw healing numbers and because I liked using various tricks to stay out of the 5SR. There's something enjoyable about abusing Spirit based mana regen. I understand that the change to CoH was to give Priests a triage-esque decision when dealing with raid damage. However, due to other healers' inability to let any damage go unhealed (especially when are HoTs on that target), Priests have been reduced to playing whack-a-mole with Flash Heal, PRoM, and PW: Shield in between CoH applications.
The bottom line is that I find this new means of coping with raid damage mentally tiring. Competing with other spot healers to see who has the fastest reactions isn't my 'thing' as a Holy Priest. If I wanted to spot heal, I would have gone Disc. At least then, I'd have some crazy Haste, awesome mitigation and insane mana efficiency. I can't say that I'm unhappy, but, I'm certainly not ecstatic about the changes.