I worked at Amazon for less than a year before I switched to an ergonomic keyboard. My wrists were already in tenuous condition after 10 years working at a grocery store, and once I started typing all day long, I started feeling the burn.
I used several incarnations of Microsoft Natural Keyboards over the years, and while they helped my wrists, I noticed my posture was suffering–I tended to clench my shoulder blades together. A few years back, I switched to a Logitech wireless keyboard and mouse combo. It worked well for convenience; but the keyboard was mushy and required frequent replacement. Caveat emptor. You get what you pay for.
Meanwhile, some colleagues had made the switch to mechanical keyboards. I missed the clickety-clack of the old PC keyboards; but most of the mechanical keyboards I saw around the office were not ergomically friendly. Then I discovered the Kinesis Freestyle Edge.
There are other reviews online of the keyboard itself and its myriad features, many of which I will probably never use. For me, the revelation of a split keyboard was that it improves my posture. I can move the two keyboards quite far apart, so that my hands and wrists are on a plane with my shoulders (or even outside the plane of my shoulders). I find that I am sitting up straighter as a result. I can also change the angle of the two keyboards to keep my hands and wrists straight.
I am one of those folks who swaps the locations of the Caps Lock and Control keys. This keyboard theoretically allows you to configure that mapping on the device itself, such that it does not matter which computer you plug the keyboard into. I was never able to get this to work, though, and just configured the mappings in my System Preferences like any other keyboard.
Finally, as a Mac user, I have to purchase replacement keycaps. I got mine from Max Keyboard. I chose Option D, size 6.5. I then remapped the Alt and Windows keys to Command and Option, respectively. Again, I used the System Preferences for the mapping rather than the on-device configuration.