I've recently got rid of several extremely expensive mechanical keyboards to go back to a new ThinkPad chiclet. I am somewhat embarrassed to say it's been fantastic.

There's essentially no range of motion in a MBP keyboard anymore: there is no difference between not pressing the key, actuating the key, and bottoming out the key. Some people (such as yourself) seem to prefer it, but to me it feels much rougher than comparable keyboards, like typing on a hard plastic surface. There is no give or play in the keystroke. Compared to a Lenovo T460p's keyboard (the other machine I own), the Lenovo is a lot "softer" to type on. (And quieter, too.) Mostly, I dislike the feel.

Now, my wrists also hurt. Now, when I'm not travelling, I was using an external Apple keyboard, not the MBP's primarily, so I'm hesitant to blame the MBP's keyboard directly. The external Apple keyboard has a greater keystroke distance from start to bottoming out, but still has like zero distance between actuation and bottoming out. (For some keystrokes, particularly ^+Tab and ^+Shift+Tab, I find it hard to keep control actuated, despite it being fully depressed; it just seems to require a lot of pressure to keep things in electrical contact). The pain in my wrists didn't start until I started using Apple keyboards, and has mostly stopped since I've replaced them. (I now primarily use an ErgoDox EZ, primarily for the split/ability to independently position my hands. I had tried, and had similar success w/ a Kinesis Freestyle, but I didn't own it.)

(I used a MBP keyboard for ~4yrs, with an ergo keyboard of some kind for when I'm not travelling for ~half of that. I've used Thinkpad's of varying models for ~10 years. Now, I could just be getting old, but replacing the Apple keyboard is what made the difference thus far for me. It doesn't make a lot of sense to me, admittedly: my wrists are, I feel, in the same bad position on the Lenovo as they are on the MBP/Apple keyboard.)

"the most ergonomic keyboards are those that require the least amount of repetitive motion"

Not sure I can agree with that. I was using one of the Apple keyboards for quite a long time while running liveops on an online game (which meant rapid response whenever incidents happened, jumping into shells and constantly typing like my life depended on it), and developed fairly severe wrist problems within a couple months. To the point where I almost had to leave the job on disability, per my doctor's orders.

On the recommendation of a friend, before taking that step I tried switching to a Kinesis Advantage for the better wrist alignment and less "hard" keystroke bottom as compared to the chiclets on the Apple keyboard. It was a bit of a learning curve (~2 weeks to get up to full typing speed when using it every day, a couple more to push past it), but at the end of it my wrists got better almost instantly, and I never had problems again. My typing speed went up as well.

I'm not sure how much of that improvement is due to the better alignment of keys (there's almost no hand movement when typing, and your wrists are always neutral) and how much is due to the bigger key action and softer bottom, to be fair.

Edit: it's worth mentioning that I'm also a boxer and a piano player, so my wrists take a lot of abuse on a regular basis. YMMV and if you're not having problems, I definitely found the Apple keyboards to be very easy and fast to use.

If you can't adjust to an Apple keyboard (and don't have RSI), the problem is you -- not the keyboard. Retrain yourself to type softly.

you don't need to bottom out regular mechanical keyboards, which means you're not constantly slamming your finger against a hard surface. You do need to bottom out scissor switches.

Not all repetitive motions are equal. It's far more complex than that. The relative angles your joints are held at during the motion, rotations, etc, are far more important than just some simple metric around number of repetitions or distance travelled. Saying less motion is better is like saying lifting less weight is better. You'll sooner fuck up your back lifting 40 pounds incorrectly than 80 pounds correctly.

Custom build at wasd keyboards work? I love that place.

Key travel time is itself a form of latency, distinct from throughput because it doesn’t count the time you take to move your fingers between keys, because you can start pressing a one key while the previous key is on the way down (as long as it’s not the same key), etc. But even aside from that, if key travel time is the biggest contributor to a keyboard’s overall input latency, then that’s what it is. There’s no real way to avoid it (except maybe pressing the keys harder?), so it doesn’t make sense to exclude it just because it’s mechanical rather than electronic.