3 questions for Oscar - first, in general, I like your simply way of teaching the game and it has helped me in the past.
Question 1: you don't seem to stress what other call the "prep" phase where you pivot the shoulders to the side. I have studied many pros and a shoulder pivot where the shoulder turn to the side and the hands stay in front of the chest seems to be almost universally used. Why do you not teach this as part of your method?
Question 2: you don't teach to change grips for a 2HBH in your book, but again almost all pros and better players use a continental on the dominant side (r hand conti for right handed player) and an eastern or semi-western grip on the non-dominant side (l hand for right handed player). Shouldn't advanced players use a conti R hand/E or SW L hand grip?
Question 3: you and many others teach the 2 HBH is a a L handed forehand for a right handed player. But, many pros use the dominant hand, arm and shoulder quite a bit. Djoko hits 90% of his 2 HBH with a square/neutral or slightly closed stance, his right shoulder closes a bit to the incoming ball, he does not have the racket head as high up on the backswing as a normal pro forehand, and the L hand seems to take over on the follow-thru. He does rotate the hips, shoulders to fully open and wraps the follow-thru like a WW forehand, but there seem to be a vast difference in his 2 HBH and his forehand. Isn't the 2 HBH really quite different from a normal forehand?