Is there actually any evidence ergonomic keyboards reduce risk of RSI? Last time I looked into it it seemed like marketing fluff with no actual studies that backed it up.
If someone invented a magic laptop that had a built-in Kinesis keyboard but could still close up, I would spend ridiculous sums of money to own one.
For me shift, space, backspace, tab, win, ctrl, alt, esc and enter are all thumb operations.
However I wouldn't go as far as saying it has solved my RSI, but it is definitely part of the solution that allows me to program 40+ hours a week (more like 50-60, 40 hour week professional + hobby programming).
FWIW the other parts include regular exercise, alternating mouse hands and using a trackball on my 'off hand', and a keyboard-heavy system (vim, dwm, etc.).
Like Jeff, I was not content with any of the available keyboards. I have two Kinesis Freestyles (the old one and the new one), and they are both great. But the halves only separate by 20", which is not enough to mount them on armrests.
So, I cut the separator cord one night, only to find that it contained twenty fine, individually shielded wires. At length, I reconnected them with an extension piece (three CAT-5 cables), first with breadboard (proof of concept), and eventually with soldering, heatshrink wrap, etc. I am NOT a hardware guy, and this took forever. But it was worth it.
Freestyle nitpicks: (1) The hardwired keys along the left (C-x, C-C, C-v, etc) are pointless and easy to hit by accident, yet hard to find on purpose. (2) "B" should be on both sides. (3) It would be nice if the two spacebars were distinguishable. I'd map one of them to Ctrl.
Mapping caps lock to ctrl is invaluable. (Except when you're on someone else's machine and you're constantly WRITING IN CAPS.)
You definitely have to be careful with your left pinky. I've started "palming" the corner control, when possible -- even for things like C-v and C-b where you can catch the other key with your thumb.
I've also tried key-chord-mode, with strong but uncommon pairs ("fj" "fk" "dk" "dj") set as a prefix for a custom map. The jury is still out on this, mostly because it's hard to change my habits.