I'm bit curious since I haven't tested it much, but does he chose his heal targets based off of a percentage of health lost instead of the amount?
I could swear when healing his second target, I've had him heal my sage naruto over my konan at times - the sage had a greater percent lost, but the konan had far less total health remaining. I could be mistaken though, just thought it was strange.
This guy is amazing though. I run him with Earth main, Sage naruto, and konan.