I find the whole "88 key" thing interesting. Bosendorfer did extend that lower octave on down to the C below, which is kinda cool. Mostly, I see that covered up so that you can't play those notes. But I wonder how long it would take a good jazz player to be down there messin' around. I also tend to run out of keys on the top end with some runs, just 'cause.
Most interesting thing is, it would be VERY easy to extend either end on a keyboard, not so easy on an acoustic piano.
Totally worthless thought, but I thunk it, so... LOL!!