I think Richard Mellish really sums it up - it's very unlikely that any player with any experience is going to change to different keys now, as they will be used to the existing layout - so Guran is really only likely to influence new players IF they haven't already decided to go with the majority of experienced players. It would also limit their choice of instrument dramatically, even if they could find a concertina with the larger buttons, as I don't see any of the current makers adopting his ideas on button size etc - no matter how much ergonomic sense they may make. and it makes no economic sense to try to convert any of the traditional concertinas.
I think this has become argument for arguments sake
chris