All this discussion has given me further inspiration in the direction of coming up with my own idea of what an ideal keyboard should be!
Allowing one extra column of keys to the left of the keyboard as well as an extra row on the top, one has a tenkeyless keyboard that is easy to understand, with the Fn key only required for the actual function keys and for Pause/Break (which could be Fn-Esc)... providing the compactness of an HHKB-like keyboard "for the rest of us". I realize, though, that by going for my own ideal of an Enter key, instead of sticking with the standard arrangement, I may be asking too much of people.
I've made some small changes to the keyboard since its initial form. First, I shortened the Caps Lock and Shift keys, and then exchanged Caps Lock with the left Windows Shift key, to make the left Fn and Windows Shift keys more reachable, as well as dealing with the problem of hitting the Caps Lock key accidentally.
Then I decided to get rid of Scroll Lock, and bring in Pause/Break, since that key is more useful than the seldom used Scroll Lock. Since Fn-Num Lock is now F8 given its position, I suppose Fn-Esc or Fn-Pause would be used for Scroll Lock; it wouldn't be possible to copy the IBM tenkeyless precedent.
