Interesting thread, I am looking forward to reading more in this series!
I am a beginner and was given a horse with next to no information about him. Every single bit or bitless option I have tried with him has resulted in head shaking until I tried a mechanical hackamore. The first time I came near him with a bit he started shaking his head and stamping the ground as soon as he saw it. He has been very calm and responsive in the mechanical hackamore. Zero head shaking, no fear, and he stops! This confuses me as everything I read says these are supposed to be horrifying.
So anyway, I'm trying to learn as much as I can about hackamores. Thank you for the informative thread.