@Andreauk: Thanks for sharing your macro. I like the idea of applying the dot then do something during X seconds then apply the dot again. To answer your question, cast heal spells do seem to apply Atonement as I currently don't use Plea in the DPS rotation and keep seeing 4 Atonement at any time on the tank.

@luxlunae: I like the approach Bubble -> DPS to heal over time. Currently I'm doing differently with Shadow Mend -> DPS. Then in case of problem I cast 4 bubbles with another key. As I said, 4 x Shadow Mend over heal the tank and you don't recommend it either so I'm going to give a try at your strategy. Then keep another key to cast 4 power word radiance in case of team emergency (each priest will cast on itself as if they cast on the same character, it might not heal some characters being too far). FYI, I use two click bars to cast Plea, Bubble, PW Radiance or Shadow Mend on a specific character so that's covered.