He writes "my experience is that most yoga teachers encourage moderation". I've lived in an ashram in India and gone to a number of classes here and there and my experience is that the majority of yoga teachers are dangerously incompetent. Sure they talk about moderation, going slow, listening to the body etc but generally they still get people doing poses that are probably dangerous for a person in excellent shape and they almost universally fail to train people in the fundamentals. Partly its the fault of impatient students who don't want to spend a whole series of classes just learning to sit and stand properly (even if it's what they actually need). I still do a little bit of simple yoga now and then - it truly is excellent for fixing occasional back problems but I don't think I'll ever take another class, at least not without knowing the instructor very well.