Boris, I'm pretty sure that when you saw that hexagonal "C-thru" MIDI
keyboard layout you thought the same thing as I did. If there are MIDI
synths with decent harmonica voicings (I don't know if such things
exist) one could make a 49-key electronic Harmonetta. They even call
that Axis C-thru 49 product an "Harmonic Table Keyboard." I found a very
detailed and interesting review of the device here:
Now that electronic Harmonetta idea is probably completely wrong-headed
to a person like Michael Rubin who is no doubt burning a lot of midnight
oil working out with his ~real~ Harmonetta these days, but it would be
at very least an interesting experiment. And dare I say it, easier to
play? It does carry a heavy price tag, though... ($439)