I'm going to quote Dr. John Kella, Corp Ergonomist at the NY Times, since I believe that the Posture from the mid forearm down is more critical if you are attempting to reduce RSIs in this area. This is a combination of overstabilizing the proximal muscles of the upper arm, and forearm, plus overwork of the smaller, weaker distal extensor muscles that move the wrist and fingers. These problems are then combined with the click-activation now being required by the thumb. Still, I'm finding that all office equipment requires some degree of employee training, not unlike car safety training.
Training becomes key to safety and efficiency.