I'd like the idea of everyone having an extra 4 hearts added to everyones health.
Because nerfing damage affects a wider spectrum of things related to things other than PvP, such as mobs and PvE events. Adding 4 extra hearts is a lot easier than reconfiguring the entirety of MassiveMobs to the new damage system.
If we fix MassiveMobs damage and any damage issues in PVP itself, then there isn't any reason to tack on the extra hearts.Massive mobs needs a re-evaluation of damage anyways, IMO. Giving more hearts would just be confusing for new players and seems rather cheap to me.
Let's fix the problem and not apply what we think is a bandage. Because if we do the bandage the problem still exist and is still, well, causing problems.