Just taking the 'backing thing' --
I find that getting a light 'quick' backup is all about preparation and real training. Once you get a horse to round its back, bring its belly up and get the weight off of its forehand (lift its shoulders), it is simply a matter of 'pushing' or 'driving' a horse back. You only 'close the front door'. You DON'T try to pull the horse back. People that get resistance are trying to pull horses back and they get resistance and feet that barely drag back. If you want t a horse to pick up his feet and step back lightly and quickly, you have to do the preparation. This comes back to good training and good preparation and not having a horse reaching for a treat.
Backing is completely related to stopping. It is exactly the same thing. The horse needs a rounded back (as opposed to a hollow back), a belly that is lifted up, and shoulder that are lifted up. When you do this, a horse will stop on its back-end and if it has sliders on or good ground, the back feet will slide and the front feet will travel because he is trying to stop and he has his weight off of his front end. More bit or more pull just gets a stiff, resistant stop with a horse jamming its front feet into the ground. It is a matter of teaching and preparation.
If you got a treat to get a good back-up (and I would have to see that), how is it going to relate to or help a stop? You cannot give a treat during or quickly enough after a stop for a connection to be made.
I am open minded, but I want to see something more and better than you can get with 'good training'. So far, I just think if people think they are getting better results with treats, they just do not have the skill to teach the maneuver with proper preparation. So in that way, it is just another means to an end on very basic things. Personally, I think they should invest in time with a good trainer that can teach them to properly prepare a horse for the next more difficult task or maneuver.
Like I said, I have an open mind and would like to see before, during and after videos to see what treat are doing that training with pressure and release will not do.