I don't have any experience with ergonomic keyboards or alternative keyboard layouts, but I can recommend one slightly less drastic option: a small wireless keyboard that sits in your lap. I have one of the small Apple keyboards and for normal computing I use it on the desk (or even use my laptop's keyboard). When I'm in paper-writing mode I put the wireless keyboard in my lap, and it helps a lot. I used to get occasional wrist pain and now I don't.