" which likely is the oldest argument of all against progress...

Is it progress or is it just 'different'? Does being different make it better?

I would be interested to know how many players have done as you advocate - modify a £2000+ concertina with no certainty of an improvement.

I suggest that you get a maker to make a concertina to your 'design' and see how many it sells - this would be the ultimate test of your theories.

Bear in mind that what suits you, ergonomically, may not suit the next man or woman - their hands may be of different size to yours.

A 'standard' format may not be a total answer and a number of players will fall outside the format (and they may have to work a bit harder) - but an awful lot will fit into the 'standard' and be quite happy with Wheatstone's original layout
This is an issue that you have to take into account.
chris