It's been 10 years since then. I now have zero problems, no special exercises, no ergonomic keyboards, chairs, desks, etc. I also regularly play ARPGs like Diablo 3 and Path of Exile, which make most people with RSI cringe.
I agree that Sarno's framework is not perfect. I'm not sure I buy his explanations as to why it works, but it does work. The key is that there is a huge mental component to RSI (or, at least, to some cases of RSI) that most people don't acknowledge. The monitoring/worrying about damaging yourself does something to those muscles/tendons that builds up over time.