Did you know that some of your ideas have already become reality? For example the Vibrandoneon will be built in a (not 6-but) 4-row version – and perhaps it will be able to give it a Janko layout although then you would only have a range of a little more than 2 1/2 octaves. Victoria (former manufacturer of the Vibrandoneon) seems to have built some Janko instruments a few years ago, but ridiculously with only two rows!
(By the way, thanks for explaining the sense of the sixth row, I didn’t understand it before, now I know…)
I’m not sure if you need a special mechanism for playing drones as long as you have sort of a neck strap; so you wouldn’t need to hold the instrument and could simply play drones with your left hand, that’s what I do…
The Blues Box bending method seems to be quite interesting although I don’t speak English good enough to understand completely how it works – but the possibility of bending that fast and effectively is fantastic.