I've been continuing to read the responses and would like to remind everyone, that if people didn't care, they wouldn't be here posting. So, to those participating in the discussion, thank you for your time and care. It's always appreciated.
Now I'll try to address some things where I can.
There was a blue post that said it was a correction and not a nerf, but it was not clear whether the blue was posting as to the present Lightwell or as to the apparent nerf on the ptr.
This was, indeed, a correction to the tooltip and not a change to Lightwell. It has not been nerfed in the next patch and while there have been some changes done, they should predominantly result in better healing overall (in relation to priests). To check out the hotfixes that were implemented prior to the PTR, you can see them here. http://us.battle.net/wow/en/blog/1232869
You'll notice Lightwell's health was boosted up by 50%.
The change we are making are a little bit like balancing scales. We trim a little on one side and add to the other. If you look through the PTR notes ( http://us.battle.net/wow/en/blog/2011384
) closely, you'll see this within them.
Currently, Holy has a lot of mana on live, but to counter the change we're making to Prayer of Healing, we're buffing Circle of Healing. We’re making Chakra easier to use. We’re also giving you the option to make Prayer of Mending a little better. Holy on live is pretty strong overall.
As we said in the Wow, Dungeons are Hard blog, ( http://us.battle.net/wow/en/blog/2053469
) any Holy priest with 1700 to 1800 Spirit shouldn’t have mana problems. If they do, something else is going on such as dps being too low or players taking too much avoidable damage. You can reach those numbers without ever stepping into a raid. Finish Twilight Highlands. Get the Cord of the Raven Queen epic belt from being Exalted with the Guardians of Hyjal – you’ll be Revered just by completing the Hyjal quests. Max out your Tailoring and make yourself some better gear or just buy some from another player. Get the Mandala of Stirring Patterns trinket from Tol Barad (the quest area – it doesn’t require setting foot in the PvP area). Look for Sprit enchants. Reforging is your friend. Reforge everything to Spirit until you feel that you won’t run out of mana.
Keep in mind, you're not alone in the dungeon and the dps and tanks also need to take responsibility for what they are doing and how much of your mana they are requiring you to use. You also don't need to keep everyone topped off. You just need to anticipate the damage and adjust accordingly.
We want people to pick and choose the spells and abilities they need to use in correlation to the events going on in the game. If someone still has Prayer of Mending on them and they haven't taken damage yet, do you need to recast it? Does someone need a shield or renew vs. a full heal? Can you use something else in your bag of tricks that you normally would just bypass as "useless" that would instead by useful in a certain situation? Can you use binding heal? You may just need to cast a high expense spell to get the job done, but if you have the mana to do so, why not? Those spells are meant to have use.
I've also looked into Discipline in light of the change to Prayer of Healing. In general, there shouldn't be a time that there is so much AoE damage that everyone is going to need it immediately. Raids may be a little different, but you should have plenty of support from other healers as well at that point.
The cost of shield may have gone up, but so has the damage mitigation for it, though in light of Cataclysm, damage mitigation isn't all a Discipline priest needs to do anymore. They need to be in there, mixing it up and healing versus just using a few spells. Don't forget you also have Power Word:Barrier if you can convince people not to run away from the glow y dome of goodness.
Divine Aegis was also buffed a bit and with Inner Fire should help with Prayer of Healing.
Keep in mind, this is just a short list of changes, and the rest can be found on the PTR notes and more are being added practically daily at this point. Changes are still ongoing as well. Continuing to provide constructive feedback on these changes and how you've been experiencing them (for those that go on the PTR) is always very helpful.