Originally Posted by
Isheria
This trinket improves crit healing by 9% (upgraded heroic), critting more means you get the most out of this trinket which benefits your echo of light as well while in addition provides extra throughput in the spells themselves while mastery simply bumps the hot that follows after your healing spell has landed.
Having your actual spells crit 10% more often for example infact provides more healing than having your mastery hot buffed by 10% and significantly improve your burst healing as well.
I'm currently testing full crit build instead of mastery and the output is significantly increased over an equivalent mastery build because of the way the trinket, almost all healing spells and mastery interact with each other.