[ipv6ipv4]

I would hazard a guess that it would make RSI worse because it minimizes the kinds of hand motions to operate it. Alleviate RSI with a keyboard by constantly changing the position of your hands on the keyboard - the exact opposite of touch typing dogma. Pecking at your keyboard is healthier.

[jarpineh]

I'm no health expert, only an expert practitioner of my hands. Mostly I keep changing keyboards and positions. That small chorded keyset can be set to more natural positions and moved at will to wherever you can reach. You ostensibly don't need to even look at it. I'd assume you would be looking between the chord sheet for directions and what you're actually writing... A device like this Tap thing, which is attached to your fingers or wrist, allows even more freedom.

As for mouse, well, I guess a trackball is easier to move about, stick to chair arm or something. Touchpad might work also, but you require more estate for precision and gestures.