I really hope that they're able to better balance out spirit and mana regen for priests. Disc and holy while being the same class vary in spirit consumption more than almost any two healing specs in the game. Disc has typically had very low spirit requirements especially do to atonement being very efficient but comparatively holy could get use out of max bis gear full spirit gems fully reforged to spirit and make use of that. Wouldn't be ideal and smarter healing would probably prevail and get more use out of other stats but the fact remains that holy can suck mana down faster than a fat kid eating a piece of cake if they want to.
They've said that spirit won't scale nearly as high as it does and has currently with players really only needing to worry about it in the first tier of raiding and by the last tier able to fully spam away at their best most inefficient heal and still end up over 50% mana at the end of the fight. Also they've said that they're taking away spirit from a lot of sources so there really won't be many ways to bump your spirit up. From a customization stand point this seems rather lame since it really effects the way that you want to play your character. I mean look at disc today. People range anywhere from 5k spirit up to 10k with the lmg and holy has no limit on where they want to play with spirit. Really in the priest class there are active raiding priests with 5-20k spirit variance yet that's going to go away.
Now, they're bumping up mana regen passively also to compensate for the removal of things like innervate and also they said that they don't want new lv100 healing to be as horrid as it has been in previous expansions but will it be enough? The typical healing model has always been fresh max level fully gem and reforge spirit and then by the end you almost ignore spirit and get enough passively. Similar to dps and tanks with hit/expertise yet that's just being removed. It seems like with the removal of reforging and dropping spirit out a lot of pieces that the base mana regen is going to need to be waaaay higher than it is now. Their current model is paladins starting out with holy light spam and filling with a few flash of lights to end game being spamming flash of light with a few holy lights as a filler. But, how does that work with priest who as well as their standard healing rotation also have huge mana drains like mass dispel? Same with our L90 talents most of the time DS was used simply because its so much more mana efficient when comparatively halo heals for way more but if used on CD would drain your mana too fast.
And now how does this effect PvP? Most of these changes seem to be purely aimed at the PvE environment. As it stands especially in 2s a healer/dps comp takes forever to kill and the healer, even with practically no spirit in full pvp gear, hovers around 90-100% mana the entire fight. Typically one of the only ways to kill a healer in the past was to oom them yet this change seems to make healers even more broken in pvp.
Blizzard has stated that they don't want healers to feel like they constantly have to spam heals and keep people topped off or else they're going to die. They want people to hover more around the 30-70% range. Yet "spamming" spells isn't necessarily a bad thing and really is just playing the game. DPS and tanks constantly have something to do yet as a healer if there isn't much damage going out it's just boring as hell. If anyone remembers the 5 second rule or keeping the boss at 25% and letting the healer wand it down to the enrage to regen mana was such a boring way to play because there just wasn't anything to do. Blizzard has already stated that they want things like atonement and fistweaving to be used during times of relatively no damage which sounds like healing is potentially going to be boring as fuck come WoD. I mean cool I guess disc and mw will be able to contribute to the fight during a low damage phase but what are the other 5 specs going to do? Sit around and twiddle their thumbs?
The reason that the current healing model exists is because they wanted to challenge healers and give them something to do. The game is meant to be played and enjoyed not sitting around in a raid where 16 people are having fun and doing stuff and the 4 healers are sitting around browsing forums because there's no excitement in healing. It sounds like WoD will have all the excitement that a druid would have in a modern raid with 2 disc priests and 2 holy paladins.