I started to play the violin without shoulder rest, and middle chin rest. When I started to study formally, my professor put me a conventional one. The fact, is that I never been comfortable 100% for 12 years. I've never been able do quit it again, because I have a standard-long neck and I was afraid to screw up my technique. But recently, the normal shoulder rest was "killing" my neck, trapezius and shoulder muscles.
So I ordered the Magic Pad and tried it. The result, was finishing with the most of my muscles tension and obviously having a sound projection upgrade. Technically, I felt the instrument very stable has I didn't for many years and of course it brings goals to intonation and bow, or with less effort.
I think it is a great solution for some middle chin rest players, because you can put it just in the area you need to compensate space between body-instrument. I don't know if it will be my definitive, but it is being very helpful to me at this moment. It's very cheap just be careful about the sticker (not bad idea order an extra).