@Phil - The new thin stainless pad backing disc does the same job as the key cup it's currently fixed to. It doesn't have sides to it like the cup so it lacks protection there but I can't really see why a key cup has sides other than to easily locate the pad within it. Is there really that much "attack" on pads from the sides?
Mine are located by the central hole/screw. No sides needed.
Or did you mean something else by "shield"?
Don't forget a newly made sax could do away with the weight of the key cups and so this may be attractive to buyers of new models incorporating my design, but I do appreciate you may not wish to cut off your MkVI cups. That's why my system is designed to fit into key cups with no modification as well. So you don't have to alter anything.
The real market for this design is in the future. We often don't want to modify anything old, be it horns, cars, anything with a perceived "value" as is. We do however like to update our Victorian houses to incorporate modern devices and materials and also build new houses using modern technology, but only if we're sure there's an advantage.
Convention takes time to change, and manufacturers will be led by what they think their customers want.
I'm totally with it that folks don't like change much, especially after 150 years. That's why we're all still riding horses, right?