I agree with AndrewZorn. Use autohotkeys, or xmodmap if you are on linux to emulate the key layout. Its a no-cost way to find out if you like the layout or not. I was able to sell my HHKB when I got xmodmap to work. Now I emulate the HHKB on all of my keyboards. Its pretty neat.
To be fair, the HHKB has more than the key layout going for it though. The small form factor and topre switches are important considerations to consider.