I use Microsoft Natural Ergonomic Keyboard 4000 for years and do not suffer from RSI. Another thing that probably helps is that I use table with enough depth,

I use Microsoft Natural Ergonomic Keyboard 4000 for years and do not suffer from RSI. Another thing that probably helps is that I use table with enough depth, so between my monitors and edge of my table there is enough depth to not only fit my keyboard, but also extra ~15 centimeters space for my arms.