I can recommend the Kinesis Advantage too, but I later sold mine -- weight lifting did an even better job of eliminating ergonomic problems, as did piano practice once before, and I think it's generally a better strategy to not need ergonomic devices.
I imagine ergonomic designs probably makes the most sense for people that do large volumes of typing with high WPM. For me I just really like the compact layout of my FC660C, small boards allow me to have a mouse either side, swapping mouse hands is another great way to avoid RSI.
I have to say, I found the Kinesis Advantage to be fantastic. It really did work, solving my ergonomic problems, wonderfully and very quickly. The need for it did depend on the volume of typing -- back when I used it, I switched off of it, but then had to switch back after some days with more typing.