There are a lot of touted ergo features: tenting, concave keywell, l/r split, ortho columns, thumb cluster. Of these, the most important IME is the thumb cluster -- giving more work to your thumbs and taking load off your pinkies. This led me to HHKB JP layout for 80/20 ergo benefit without having to carry two unwieldy halves of a keyboard when I want portability. Still use Kinesis Advantage 2 at home, but nothing be…
HHKB JP is very nice in that it has a slightly reduced row stagger, is a single board, and has extra thumb keys which can be remapped to for layers or moving things such as shift or backspace into more comfortable positions.