Not to be flippant Muir, but I have direct experience of, not just a conceptual framework, both with and without the "Healed" call, as a PC and an NPC. I will tell you that the addition of the LCO "Healed" call has made combat better on both sides. As I have that direct experience I'd like to explain why. As a PC, lets say that one of my primary offensive attacks is elemental stone charges from my staff (because it is for my PC), and a rocky looking sea creature comes out of monster camp. I toss some stone damage at it, because while it might be an elemental healed by it, it might be a construct or animal that isn't. Under 1.3, I have no way of knowing if it's helping or hurting. Under 2.0 I now need to Throw - have it hit/be acknowledged as a hit - ask if it healed it - get a response. Under the LCO, it's Throw - get response that it is healed. It cuts down on the chatter, and we can all get on with murdering the rock lobster.
Now, as the NPC, I come out as a rock lobster that's healed by stone. In 1.3 I will be using a lot of my limited processing power calculating damage and healing as they throw stone at me. Under 2.0 I either do as in 1.3, or I get hit - - get ask if it healed me, which pulls me away from what I was just doing - tell them yes. Under the LCO, it's get hit - call healed - move on to killing the PCs. Furthermore, since I can't be healed with carriers, it doesn't apply to weapon combat, and it's just as simple as current "no effect" when someone charms my lobster buddy to attack me with its stone carrier claws. This also has the benefit of reducing the number of times PCs will throw those non-standard healing effects at me, so I don't have to do as much math on the fly while still allowing me to use my elemental stone attack to heal myself instead of to hurt the PCs if I wish.
Overall, having played both with and without this rule, having a "Healed" call for non-Healing, non-Necromantic, effects has improved the game in Oregon and Seattle. It's not theory-craft, but real world experience and actual play that has shown me that.