so, i'm still not an advocate of using LotM other than on the move or when you know it's the difference between life and death.
that said, the more i think of what healing alongside others is actually like, there are "enough" situations that occur where you know you have incidental healing on you (HoTs still ticking, ground AoE heals) that perhaps you could write off the self damage it does. so, if an infallible robot was to play a hpally for a raid, the robot would probably be able to identify niche situations where the mana efficiency from a LotM, given the fact that the robot knows the self damage will be healed by spells that are already cast (i.e. no further mana will be used to make up for the self damage).
in the end though, this is extremely, extremely niche and i still cannot get over how LotM does not benefit from two golden dragon traits.