Wow! A real current thread about tank changes. I had almost lost my faith in humanity.
Back on point; I agree that instant heals should benefit from the Defiance buff. Most often When I use it, my equilibrium instant cast negates any spell the healer was casting that would benefit from the extra 20% buff. Though I disagree with paladin buffs, they have their private club only block rate, let's not homogenize.

#DarkWarriordin <3 Phoenicia