[nrkn]

I have a 4000 and have been using various split keyboards (previously Belkin models) for as long as I've been coding. I've never experienced RSI despite spending most of every day at a keyboard, but as I never had it in the first place I can't say for sure that it's down to the keyboard.

The only disadvantage that I can see is that I'm so used to split keyboards that I find using an ordinary keyboard uncomfortable, that includes my laptop and netbook too, neither of which I do any serious work on without first plugging in an external keyboard.