Yes, I have had a long battle with RSI. The Kinesis keyboards are amazing devices for helping with RSI, but they don't provide mouse capability, so I still have to move my hand(s). Also, the Advantage Pro keyboards are fixed width (shoulder separation).
The KeyMice are extremely customizable. Like you, the company is driven by people who are passionate about solving a problem, (albeit from a completely different direction), and they are geeks with ideas. Right now, I'm using the Alpha again (after a few months on the Track), and I'm evaluating its impact on RSI. (Not in the general sense, but in the "me" sense.)
Obviously, I love the Cherry blues. Not sure if others in the office love them, though ... but the ability to place the hands where I want them (including spacing and rotation) is quite handy. The downside of the Alpha is that the whole thing moves to move the mouse, but other than that, it's very good.
I am currently using 4 layers, but 99% of my work involves just 2 layers. That's not bad, since I'm programming, and that uses a bunch of strange symbols and key combos.
I had originally backed them on kickstarter or whatever it was, but they canceled and refunded everyone because they couldn't hit their schedule. I kept in touch and bought when they had a beta version, and then updated to the latest (they have a "refresh" option, I guess) and bought the Track recently. Excellent customer focus and customer service. But admittedly a difficult transition from a normal (or even Kinesis) keyboard.
I can't yet match my old Kinesis typing speed (for code or for text ... the latter used to be over 100wpm), but I am slowly rebuilding muscle memory to get there. Considering the reduced number of keys on the Alpha (necessitating multiple layers), I'm doing pretty well. Probably over 50wpm on text right now, without trying.
Mostly up-to-date KeyMouse Alpha layers
Ergonomics are very important to me. I've written a lot of code (and a few widely used products, with another on its way). At one point, years ago, I lost the ability to use either a keyboard or mouse from RSI, so I don't intend to repeat that.
It's one of the reasons why I want you to succeed. We need creativity and innovation and people who can think outside of the box. Don't take this badly, but I personally won't be horribly inconvenienced if you don't ship in my lifetime, as long as you're pushing the boundary, inspiring someone else, and something good eventually comes of your work. On the other hand, don't delay the ship date because I said that!
Regardless, when I'm on the road, I still use the built-in MacBook Pro keyboard, which isn't horrible as far as keyboards go, but it's not great for RSI, either.