As you rightly point out, without trying your system I can only speculate. I am struggling to imagine how any system of straps can be firm enough to give the stability you are suggesting while at the same time allowing the hand to shift to reach awkward fingerings, but possibly yours does this. If I have to choose, I choose flexibility over stability, and stabilise the instrument on my knee (when sitting) or thigh (when standing).

Nevertheless, apart from the stability question, where I accept the traditional design is not perfect, I still don't recognise that the other "defects" which you mention in your original post are actually problems:

a) it is not ideally located

Why? What would be ideal?

b) it is not high enough

Why do you feel a higher rest brings an advantage?

c) the height is equal, while it should be higher at the little finger side

Yet again, I don't see this. It might help to reach far buttons with the little finger, but there are other times when I want to angle my hand the other way, to raise the first finger to give that one more room to move.

d) it should be wider to offer some stability

Possibly, although I should have thought stability will mainly come from how firmly the straps hold the hand

e) the strap is too lean and floppy

Good quality straps aren't

f) static work by the thumb is needed for stabilization while a thumb strap for instance would offer passive stabilization.

As I said earlier, this is how I and many other players maintain stability while moving the hand, to control strap tension. It is an important playing skill, rather than a problem.

However, I am prepared to concede that some of my comments might arise as ways of overcoming the traditional design, and that your design may do away with the need for them. Perhaps it is my innate conservatism. However I have played anglo for more than 35 years without it ever occurring to me that the straps need redesigning. Ralphie presumably feels the same. Even with your professional interest, you admit that it took 15 years for you to decide there is a problem.