I think it's dangerous, BECAUSE of the heat. You couldnt PAY me to take a class in that atmosphere. Ashtanga Yoga generates heat in the body all by itself. You don't need to add in a superheated room - I think it could cause someone to become overheated, in a bad way. You couldn't walk properly for a week. But if you can acclimate and enjoy the workout, more power to you. Personally, I do think he's a crook, and I wouldn't give him my money. This is aside from the health questions.