I think the problem is how you define "power of suggestion". I'd grant that it's real in the way using an "anchor" number can influence how people answer numerical questions when they really don't know (even to within an order of magnitude) what the correct answer is. This is the same as the example given above, "Don't think about x" where you have to think about "x" to parse the sentence.
I don't think you can validly claim it is the "power" of suggestion that explains why people participate in your stage hypnosis act. I think it's just a matter of playing out a role in a social situation with a LOT of built-in expectations.
I do a comedy juggling act, and I have volunteers do all sorts of silly things, yet there is no "power of suggestion" or hypnosis involved at all. I just tell them to do these things, and they play along. Some of the things I do (like put an adult on my shoulders while balancing on a rolla-bolla and juggling) are even very frightening to them, but there's the expectation that I won't hurt them or embarrass them in any real way, and that the whole thing is in fun.
I would need MUCH more evidence that your volunteer participation is anything more or different than this before I'd accept the explanation of "the power of suggestion".
Oh, I don't dispute that this isn't volunteer participation, which includes a volunteer's desire and expectation. And I'll go along with the idea that "power" isn't the right word, either: I have no powers. I don't expose people to a power.
What I tell my audience before every show is that hypnosis is just like going to the movies: you sit in a comfortable seat, and, (if it's a good movie), you laugh at the funny bits, your heart beats faster at the exciting scenes, you might even cry at the sad scenes, but all the while, you don't notice the guy two rows ahead of you eating his popcorn loudly.
All of that is suggestion: the audience wants to feel it, expects to feel it, and through the suggestion of the movie, does feel it.
It's simply a state of mind that we can get into, and do get into everyday, where one is really focused on something. When that happens, most people tend to be more suggestable. This is also the case when one is confused, people tend to be more suggestable when they are very confused.
My job, as a hypnotist on stage, is to use simple psychological "tricks" (for lack of a better word), like the two you've mentioned, to "convince" (again, for lack of a better word), expectant, wanting participants feel relaxed and focused or relaxed and confused or both, and therefore are more open to suggestion. Can I do this with someone who is unwilling or unexpectant? Of course not! It's not magic, and I have no power. But suggestion does work - within very specific limits.
Funny thing is, you yourself mentioned two techniques that you use: fear and trust. Both useful when giving someone a suggestion. The difference between you and me is that I tend to base my act more on suggestion than you do. (Please, I mean no insult here, I just mean that we are two different kind of performers doing two different types of entertainment here).
