I had RSI issues within a few months of starting my first IT job. Some physio therapy and a careful re-organization of my workspace/desk took care of it.

That experience brought ergonomics to the forefront of my consideration when looking at a potential workspace.

Years later I 'inherited' a MS Natural Pro keyboard. The receptionist who had it left, and luckily for me secretary who wanted it couldn't fit it on her keyboard drawer. It was just a little too wide and a little too high. So I got it. I liked it so much that when I saw it on sale I bought 2, 1 for work and 1 for home. That is the PRO, not the Elite version. I hate the reorganized "optimized" "home" etc and arrow keys on the Elite.

Although the ergonomic features of the MS Natural are minor compared to some of your extreme examples they are enough for me. I feel a twinge almost immediately when I have to use a "normal" keyboard.

It would be interesting to be able to try many of the variations to see which is "best", for me. Ergonomics is the one place in "PC" computing that the Personal is truly PERSONAL!

The "advantage" of having a touch pad immediately below the space bar is lost to me. I have that layout on my laptop built-in keyboard. The problem is that I tend to drag and tap my thumb on that exact spot so my cursor and insertion point is constantly jumping around on the screen. Very annoying.

My next ergo project is to re-train myself to touch type using the DVORAK layout.