Well its like most things in life. When power gets into the wrong hands etc. I wouldn�t say it is dangerous, although in Champagnes case, perhaps it was dangerously embarrassing.
I myself am not entirely convinced of its effects - and this has nothing to do with being a catholic, some people are able to be manipulated by this form of mind control, others not so. But I think in most (genuine) cases that these people have just been convinced within their own minds to face their fears or abandon their misgivings on certain matters of personal distress (giving up smoking, nervous disposition, fear of flying etc). This is not loss of control but coercion of the natural thought processes for the benefit of the receiver.
I only think it is dangerous when bad people use it for bad means, and in these instances I would refer to it as �brainwashing� rather than hypnotism, although effectively the essence is about interfering with another�s mind and controlling their thoughts/actions.