Fully enharmonic keyboard layout?

A few months experience playing both the syntina and my new Peacock acoustic concertina has given me some additional thoughts on the keyboard layout. Kaspar Wicki's original plan to make the layout fully enharmonic wasn't just mathematically appealing; it's really a pragmatic help when playing chromatically rich music like Klezmer or Gershwin. Don't get me wrong; the syntina is already very flexible, but there might be ways to make it even more so.

A fully enharmonic Wicki/Hayden layout means rows as wide as nine keys. This isn't an ergonomic problem thanks to the syntina's gliding hand technique, distinct from other members of the concertina family, and it's easy enough to support in the electronics and software. But the box as a whole is already rather large by concertina standards – the Peacock made me appreciate packing more notes into a smaller footprint than my Elise – and this would make it 1.5 inches larger unless I figure out some way to make the individual keys smaller. I need to investigate that more; the standard mechanical keyboard keys are really high quality and readily available, so moving away from them wouldn't be easy.

Smaller keys would also let me add a row at the bottom so that plagal tunes wouldn't feel like they were missing half an octave of range. I don't know how useful the high E and low F will be, but their existence is implied by the enharmonics. This adds up to the following:

Gb..Ab..Bb..C...D...E....+....+....+.
...Db..Eb...F...G...A...B...C#..D#....
Gb..Ab..Bb..C...D...E...F#..G#..A#
...Db..Eb...F...G...A...B...C#..D#....
Gb..Ab..Bb..C...D...E...F#..G#..A#
....+....+....F...G...A...B...C#..D#....