Progression-wise, I've solo healed Titan HM in full Darklight and an i55 weapon when the "main healer" got punted off during ♥ phase. It was actually really difficult (hardcast Medica 2 Swiftcast Medica during Tumults, Virus/E4E on cd for table flips, etc), but we managed to pull through it because I had a cheatsheet for the fight's script and kept the party alive by the skin of my teeth. There are probably other examples.