so i'm a college freshman with tendonitis in my hands and varying degrees of other RSI. from my experience, the most damaging thing you can do to your hands is to spend long sessions without breaks. this keyboard is a _bad_ thing as i see it (as are most "ergo" keyboards), because it makes it easier to do so. the reason it's called a "repetitive stress injury" has very much to do with the fact that the muscles in your hands are not intended to be stressed the way they are while typing for extended periods.
the one thing that has made a real difference for me is setting a timer that beeps every 20 minutes so that i know to let go of the keyboard for a couple minutes to relax and stretch my hands. it takes getting used to, but it's well worth it. the pain and tightness in my hands and forearms is now drastically reduced. I haven't felt the sharp burning pain in my back for a while now (letting go of the keyboard also gets me to look up and adjust my posture). I once again feel confident that i will be able to continue my education in CS over the next 3 years and eventually pursue a career in the field.
the breaks also allow me to collect my thoughts, and i believe actually increase my productivity rather than decrease it.
i've already seen a friend of mine (also a freshman, although not here) have severe damage to the nerves in his arms, so i'm paranoid about this kind of stuff.