I do agree that from instructor to instructor stance ideas are going to be defferrent. Your whole body should be in motion which makes it easier to react to your attacker (notice I say attacker, not opponent). I don't have an instructor, but I have enough experience to make up for it. Your stance should be natural. For years I fought southpaw (still do) and never knew it until I read Lee's book and that was natural. Try and find your natural stance.