Hello Ralph,
Hope this could help. Besides being a therapist I am also a Pedorthist in the states. Your concerns in finding viable data is somewhat a mystery if you where to ask the private sector (ie: footwear manufacturers, professional clubs).
My recommendations is try to contact German Orthopedic Technicians. These technicians have numerous years of schooling verses a Pedothist like myself. Their input is well respected in the worldwide Orthopedic footwear industries and most likely they would have answers to your questions.....I reside in the states and I have presented topics in Leipzig, Germany regarding orthopedic footwear in the USA. I was impressed with their advances in footwear. Unfortunately I don't have web-links to these schools in Germany. Good-Luck and please stay in touch; let me know if you are able to find answers from them....
regards