Overpitching (as I understand the term anyway) is when you pull too much collective for your engine's available power to overcome the drag, so the rotor system slows down; it doesn't necessarily imply a stall (even though I guess you could say that bits of the blade are stalled all the time). The only way to recover would be to lower the collective.
What I'm getting at is that in an 'overpitched' situation you'd have drooping Nr and the associated loss of main and tail rotor thrust, not necessarily the case in these so-called LTE situations.
As you say, helmet fire, the 206 LTE situation as we have had it explained to us is a rapid onset yaw probably caused by vortex ingestion.
I think that tends to support the Huey 'running out of left pedal' case being different to that, because you can sit there in the hover with the pedal bouncing off the stops but not be scared of whipping around to the right at a great rate - it feels controllable, while not necessarily comfortable.