Wrathstone DLC Healer Set: Symphony of Blades (Monster Mask)

Symphony of Blades (Monster Mask)
1 – Adds 2% Healing Done
2 – When you heal an ally whose primary resource is under 50%, grant them Meridia’s Favor, restoring 2325 of that resource every 1 second for 6 seconds. 18 second cooldown.

This is interesting set that will defiantly have great usage in PvE and PvP, but to what extent it's debatable.

PvP

I imagine this will do very well in battlegrounds where allies are less likely to prop orb.

PvE

This could very broken if it's a cooldown per ally. I imagine this will be go to set for healers in all PvE content. Now lets assume it's not broken it does offer interesting choice between ever popular earthgore and bodgan. In dungeons the cooldown will be easy to rotate between 4 allies. It might be intresting set in trials with 2 healers using it as it would still give it a chance to go proc between 5 allies or so per healer.

Things that need to be tested

Is it per ally cooldown or any ally?
Does it count when used on self?
How useful is the set in trials?
How useful is the set in dungeons with orbs/shards?