I can only tell you of my own experience. Early last year after suffering excruciating pain in the fingers of my left hand, I was diagnosed with RSI, a condition which I had always believed was just an excuse for malingerers to avoid work and sue their bosses. Being self-employed, I figured that wasn't the cause in my case :�)
At the time a was using a famous name "natural keyboard". After 12 weeks of accupuncture and rest, the condition was much better. What finally seemed to cure it was when I swapped my keyboard for a clunking great Dell of 1995 vintage.