I was running a pally healer and then tried to make my shaman heal when I was having difficulties dealing with the lack of pally AOE heal. Even with chain heal, the shaman is not a "hit one button and solve all your healing problems" kind of healer where a priest has that capability with Prayer of Healing. I run a lock in my group and she's just screaming at me to switch my priest from holy to shadow and let the shaman heal, but I'm just not having it. Ever since I leveled a priest to tuck inside the group and ditch my warrior tank and move the pally from healer to main, it's been easy street. Running a multi-diciplinary team is hard enough without adding more micro management.

Both healers are great, but think of it this way: The shaman will add micro-management, all that utility doesn't come without having to include a multitude of new buttons to push. The priest will reduce micro management. All the priests benefites are more or less buff and forget. I love my shaman, but it's hard to take him outta his 'spam lightning bolt' dps role that he's so good at.