My guild runs naxx25 with 4 healers and I noticed than priests top healing meters (yeah I know you will say than healing meters are not a good measure but thats the only way I can compare my effort with others). We ussualy take 1 resto drood, 1 resto shamy, and 2 holy priests, and those 2 priests do like 5% more healing on almost each fight. I feel usless since a priest is better raid healer than druid, most of my hots generate overhealing since priests top ppl faster with Circle/Prayer of Healing. The only way to beat them is to cast WH every cd and fill the gap with Nourish instead of single target hots.