I wonder how many people actually believe this kind of stuff... lol
I'll admit to it... I do.
Well, actually I'm not sold that it works, but it's an interesting idea. By its very definition RSI is caused by doing the exact same motion over and over again until your muscles, tendons, ligaments, or joints develop pain or weakness. By changing the typing surface, they in effect change the
exact motion that you're repeating, but the question is if it's changing it in any meaningful way.
I don't know if spreading the keys out or tilting the typing surface periodically does enough to change the motion, but it's an interesting idea and assuming the keyboard isn't total crap it'll probably be good for some RSI sufferers. The question is if it'll be more than a niche "therapy" and be useful to a wider audience.
If subtle adjustments like this are enough to reduce stress to your hands, then you might be able to get some of the same effect merely by changing your posture. It's interesting food for thought.