I like to have little workspaces for writing scattered about my house, and I have enough 'boards to have one tactile stashed near each spot. The HHKB doesn't feel right on my lap, but when it sits on top of the MacBook keyboard the entire track pad is exposed. What I am thinking about for the easy chair is an IKEA Dave table for the 'Book and the SMK 85 in my lap, but then I also need a pointing device. I can't afford a trackball like you have, and since I haven't used one in years I'd be hessetent to throw down that kind green right off, so are there any cheaper models that are good that I could try?
The SMK 85 does fit on the MacBook pretty well, with enough of the track pad available, but it is heavy and really bulky comparatively, but those tactile black Alps sliders can't be beat, people.