I used a BAT (http://xahlee.info/kbd/bat_keyboard.html http://xahlee.info/kbd/bat_keyboard.html) long ago for enough time that I was able to type _prose_ at abo

I used a BAT (http://xahlee.info/kbd/bat_keyboard.html http://xahlee.info/kbd/bat_keyboard.html) long ago for enough time that I was able to type _prose_ at about 50wpm. For that use, it was quite decent - especially if you were using some system that required a lot of mousing and didn't have good keyboard control options. There, having one hand always on the mouse while the other could provide input was faster and less frustrating than current keyboard+mouse. What was not at all good was programming. Symbols often require modifier keys; but on a chorded keyboard like the BAT, that meant two chords for each symbol: the chord to set the modifier, and the chord to choose the actual key that goes with the modifier. Still, I think there's a lot of room for improvement of human interfaces (at least until we hopefully someday get neural interfaces which bypass hands and even eyes).