Just FYI, re-training muscle memory is how you avoid RSI with keyboards/mice. Its important to switch up your input devices every few months and give the muscles in your hands a chance to de-calcify from the previous ergonomics.
Personally, the only real solution to fix RSI has been strength training & regular breaks during work.
It works, that's all I can say about it. RSI problems go away whenever I switch keyboard/mouse setups.
I've reached the point where I can basically work with everything thrown at me. I have preferences, yes, but I'm not the type of person who has to have perfect setup or else nothing gets done.