I'd just use damage itself, increasing the interaction, or use diminishing returns after the first target. The only reason not to use cure potency per hit scored over healing for a % of damage dealt is so that you can sacrifice damage for extra sustain.

A strict AoE mod both takes up more text on an already bloated tooltip and provides neither the extra AA, oGCD, and reflective attack interactions of % of damage dealt nor the 2-3 target niche use cases that diminishing returns after the first target struck provides.