Let's keep this thread alive until 2100!
Nick might just get his wish the way this is going though it seems to be wandering a little bit off topic.
I have to substantiate what Lama Bear and RVDT have said about longline and mountain flying. Nick's explainations are very good and very thorough but he does not account for any vertical air movement. And in mountainous terrain with any significant wind this is a given.
I can personally say that I have experienced symptoms of a loss of lift and power increase did not reduce the descent and the control of attitude became more difficult, and I was NOT overpitching, felt just like the VRS that you do in training at higher altitudes and descent rates, and it almost always happens with an empty hook or water bucket (meaning at lighter weights) but not always. I know my rate of descent (pressure altitude rate of change) was not high enough for VRS but that doesn't mean I didn't have enough vertical airflow to get into it. I've had it happen in Astars, 500s, and hueys.
Like Lama Bear said, talk to any experienced longline pilot, you will hear the same story from every one of them...