Isn't this change also kind of a nerf? Let's say you're at 30% hp. You death pact in order to get the 50% heal (note: this is while in blood presence). You heal up to 80%, which will equal lets say 400k hp. In 5.1, if you would go to a diff presence while in blood presence, you would be at full HP (am I right?). But now, in 5.2, you'll be at 320k HP while in unholy/frost presence.
It is a nerf to those who would use percentage based healing in blood presence for more overall healing, but it gives us a toggleable +25% stam presence which is probably worth alot more while being focused.