Any touch-typer will tell you that muscle memory is absolutely vital to typing speed, and also that the most subtle change can throw you off. I can type far faster on my own keyboard than my friends' keyboards, because I'm more used to the feel of mine. The keys may be in the same shape and position, but there are more variables than just that (key texture, sound, pressure, wobble).
My point is that any keyboard that regularly shifts any part of itself around would ultimately bug the crap out of me. Human muscle memory is quite suited to adapt. Having two things trying to adapt to each other makes it all a moving target problem.
I'm sure there's someone out there with wrist pain that this will be wonderful for, though. But personally I'd rather spend $5 on a keyboard that doesn't move than even $5 on one that does.