I thought I would mention something here since it doesn't seem to be covered and yet debated in an alternate form. It may be old news, but today was the first time a fury decided to buff me with it.
The bonus to healing doesn't seem to be a straight +healing effect at all. The reason being that cleric reactives are able to make use of it perfectly well. Hovering over the icon, the tool tip showed 809, 936 and 996 instead of the capped value of 749. Quite possibly the values are also modified by Gravitas, but they cannot all be as that is only one value.
In short, don't boycott clerics for this buff.
