Looked through a random log I updated from an SM KP run on my sintank, mostly done to observe how threat worked.
Going through the log was actually interesting with wondering about it, and it seems it was answered, altough it doesn't tell me if it applies practically (ex log tells me karagga is building threat on me)
But overall : Dark Charge self heals do 100% threat
Force Lightning HD healing does 50% threat.
That would mean stance has no effect, HOWEVER the "does a high amount of threat" linked to a move would apply.
Still explains how sin are so good at holding threat.
You can't make a perfect threat curve of it if the overhealing lack of threat is true, since you have no idea which heals where overhealed or not, BUT You can probably avererage it somewhat.
Log I updated a while back:
(note I was playing around with rotation, and was also grossly overgeared for the fight. The main damage source in that fight was the lag that made me take a tick or two of burning oil. That also meant I was keeping HD stacks when my health was firmly at 100% waiting for the darn burning oil damage where it was more efficient. Also was keeping an eye out on some dps that were learning to see if they did everything right (mostly mouse droid and getting out of vortex)
Soo I KNOW its not a perfect rotation, otherwise I don't update it to torparse for bragging rights, but for curiosity about various effects :P (in case some theorycrafter want to take a jab at it lol)