I was loathe to enter the fray whilst this pair battled it out but as someone who manages a very well respected business which amongst other things provides psychological help to private individuals and corporate clients which at times utilises 'hypnosis', ie I use it almost every day in some form or another I support Mark in what he is saying.
I really don't see how or why such threads crop up in a "Magic" forum as they really belong in the those catering for therapists etc. On the stage front all you need to know is that there is some skulduggery afoot; all is not as it appears. You don't need to learn how to hypnotise people in order to create the stage hypnotism effects you want. Many of the courses will happily fleece you blind, bombard you with all manner of hokum and extraneous information (in many cases highly suspect information) etc. Find a practicing stage hypnotist and persuade them to tell you how its done. Suitable amounts of cash and the promise to keep your mouth shut and not work in their area may help there.
I've studied the Human Givens approach and I like it; it's easy and quite a straight-forward approach which works with most people. It is a counselling method and not dependent upon hypnosis. I've not read the particular book being quoted so can't comment on that.
Hypnosis is fundamentally the invoking of imagination (usually visual) and peoples beliefs or desire to believe. Yes, there is very conclusive hard fact evidence demonstrating exactly which parts of the brain are responding to 'hypnotic' stimuli and a large amount of neurological data and papers acknowledging physical as well as psychological effects. Do not, however, fall into the trap of believing that the evidence produced is evidence that hypnosis exists as anything other than the mind accessing and addressing imagination, belief, understanding processes etc. To some this may constitute hypnosis, however, neurobiologists and eminent others in related fields generally do not hold with this. There is a measurable change in brain activity but the same or very similar can be recreated without recourse to hypnotising the patient using other psychological methods. The only information with credibility is that written in the formal medical and scientific publications where set standards have to be upheld. Books and other sources may have valid ideas but I'm afraid they do not count as evidence.
Mark is wrong, in my opinion, to totally refute that 'hypnosis' exists but only as it is a handy term to use when we convince people they are going into a relaxed state, for them to visualise etc etc and there are close links with sleep and dreaming here. The problem with hypnosis is that what most people generally believe it to be is complete rubbish and the term is open to so many different interpretations (intentionally so). He is also wrong to suggest that no harm can come from people using 'hypnosis'. I say that because anyone who sets out to play with their own or others' minds is quite likely to cause themselves or their victims some disturbance and harm. Nothing to do with hypnosis just that you would not want someone who did not know what they were doing play with the brakes on your car, an amateur surgeon perform heart surgery on you and so on. Only people who have trained and are aware of the potential psychological effects should be playing about with peoples brains. That is the therapy side of things. Mark is, however, absolutely correct in stating that stage hypnosis can in no way be considered dangerous unless someone gets over excited and falls off the stage. I obviously don't walk in the same circles as Mark so won't quote anyone but I do know many people who have been famously or professionally connected with hypnosis agree that there is no such thing at least as per what people generally believe it to be.
If you are looking to perform stage hypnosis be under no illusion that it is all cleverly crafted manipulation and that your 'volunteers' will either comply with instructions or not comply with instructions. It is a skill and you will need to be good at reading people if you want to be good at it. I'm tempted to say that the stage use is probably more difficult than the therapeutic use but only because clients requesting therapy tend to already want to believe in the effect and can more readily be convinced that physiological changes are psychological (thereby achieving the desired psychological effect). to learn stage hypnosis watch a few videos of others performing, get some practical training with a stage hypnotist and forget about any of the technical books as you won't need them.
I have had clients tell me that they enjoyed and benefited from my hypnotising them when I had done nor attempted to do any such thing; likewise I've had others tell me nothing other than corroboration of the fact that they were not hypnotised when we've gone through the motions of 'putting them under' so to speak. I really don't care either way what they believe so long as they benefited; I'll deploy a wide array of methods in order to help my clients.
I have been working in this field for over 20 years so believe I have a sound background of experience to base my opinions upon. I still read new literature on and off to keep abreast of what others believe but am yet to see anything to prove the existence of states of trance or mans ability to control another other than through the use of 'brain washing' techniques and those take us into very different territory.
If people wish to believe there is more to hypnosis, NLP and several other related 'ideas' so be it - it helps me that many of my clients will respond to what they believe to be my use of such methods and everyone has a right to read the facts and then make their own informed decisions. I'll just caution that it is nigh impossible to read everything which comes out on this subject; that most information is dubious and even if wrapped up as such has little scientific credibility; that some respected people really do believe in trance state hypnosis; that many (most?) who use it on a daily or professional level don't believe in it except as a term to explain a process.