but they have to be shown while the plane is in the air how slow and smooth stick movement should be and that's normally almost impossible to do when the instructor is using a buddy-box.
Sorry, but I disagree. If it was "almost impossible" to show students how little stick movement it takes while on a buddy box, there wouldn't be many of us here who could fly.
I know you're a HUGE proponent of your instructors method of teaching, and maybe it's the best way to teach, I really don't know. BUT, the buddy box method has worked okay for a long time, and I don't think you can convince everyone.
Besides, not very many instructors, or students, are going to feel comfortable standing close with their hands on the sticks together.
Our society just isn't all that comfortable being so close to someone they don't know. "Personal space" is a true psychological need.
Dennis-