I got a Unicomp model M with a trackball at the top right corner of the case and rubber dome keycaps (so I can use it at the office without annoying all my neighbors) and it's currently the longest running keyboard I've comfortably been able to use, for more than 7 years now. I had to use a gold touch 'tented' split keyboard for half a year when I was dealing with some sport induced wrist and hand issues, but otherwise a full sized keyboard hasn't cause me to develop any injury. I do appreciate that when I use the trackball my right hand cups the corner of the case and my wrist remains in a vertical position - that does feel kind of ergonomic. I have a left handed vertical mouse on my desk from around the same time I had to use the gold touch and it's a nice backup.
I did have keyboard related wrist issues in the past but it was mostly from truly bad keyboards - e.g. spent a couple of years using an Apple 'magic' keyboard. I have no interest in using a tiny reduced layout input device.
I find the big advantage of the reduced layout is that it moves the mouse/trackpad closer, reducing strain on my arm as a reach between the two.
I like the magic keyboard because it requires little effort to actuate the key and makes it easy to switch up my working position as it is so similar to the laptop keyboard.
I wish Apple would offer a combined keyboard and trackpad for desktop use that was the same as their laptops. I find being able to switch hands on the trackpad reduces strain.
I did have keyboard related wrist issues in the past but it was mostly from truly bad keyboards - e.g. spent a couple of years using an Apple 'magic' keyboard. I have no interest in using a tiny reduced layout input device.