Ghostcrawler
I'll be really frank here. I don't think the group portion of the heal is long for this world. I personally dig it and I feel smart when I see 5 people in a group all at once who need healing. It makes the spell different from other AEs.
On the other hand, it's pretty gamey. (I can only heal these five arbitrary people, why?) Priests feel like they have to ask raid leaders to set up groups with their weird AE spell in mind, which is really unlikely to happen in Raid Finder. It doesn't work at all on encounters like the shrines in Sha of Fear.
We're not going to change it for 5.2. We're probably not going to change it for 5.3. But I sense the writing on the wall here that it won't last much longer. I can imagine a future iteration where
Prayer of Healing is the AE equivalent of Gheal and
Holy Word: Sanctify is the AE equivalent of
Flash Heal. (Yes, I know Disc doesn't have
Holy Word: Sanctify - I'm in a really theoretical space here.)
Sorry. I broke my own rule about simple questions and answers. Sometimes I can't help it.
At the moment (which could still change) Rapture provides a 25% cheaper
Power Word: Shield and a 150% mana return on a
Power Word: Shield. When we tried PW:S at 50%, it became too efficient to use nothing but
Power Word: Shield. We aren't trying to kill
Prayer of Healing use completely, just shift to a balance where
Power Word: Shield and SS are used for absorbs, and
Prayer of Healing is used for healing. Yes, Disc
Prayer of Healing will be weaker than Holy
Prayer of Healing, but that is offset by the incredible benefit brought by absorbs. Please don't interpret this as "Because absorbs are so good and because absorbs are my thing, it is a design failure if I ever cast an actual heal."