What's your experience in using a thumb-operated trackball? I had the Microsoft one ages ago and I remember I did eventually notice some minor aching in my thumb.
Nice keyboard by the way, though I know that the Thinkpad's keyboard is a delight to type on as well. :)
The keyboard looks very sleek and minimal, I love it!
How is your experience typing on that layout? Where is the space button? Where is return? Where is the scroll lock? ;-) Also, how is your experience with a finger-operated right-handed trackball? I'm looking into getting a trackball again, probably finger-operated to minimise hurting my thumb, but I'm not sure if I want to go symmetrical or right or maybe left-handed (if that's even an option).
Having a trackball sitting between a split keyboard does sound like a great option. Right now I have my mouse in front of the keyboard and use it left-handed which helped with the RSI.