I learned QWERTY in high school, and by the end of college was up to around 100wpm. As I started getting older, I had some wrist trouble, mostly from mouse, but also from keyboard, and decided to switch to a more ergonomic layout. It took me a month or so (not full-time use) to get my Colemak speed up to 40wpm (minimal usable), and a couple more months to get it up to 80wpm. I've never really regained my 100wpm speed (been using Colemak for 8 years now), but my wrists thank me. I'm still able to touch-type QWERTY, but I have to look at the keyboard to give me the "context" for it, and my QWERTY speed is today only about 40wpm.

Lately, I sometimes think about going back to QWERTY just to simplify my life; mouse avoidance has been more important to me than keyboard layout switching, I think. But at this point, it would be as much a pain to go back as it was to switch in the first place.

I switched late high school to exclusively use Colemak and have since. It's harder to reflect now about the difference of it as it have just became the new normal for me, but I remember my initial reactions after getting fluent in colemak was that: 1. for me personally it didn't improve typing speed significantly 2. It felt much more ergonomic. I don't move my hands as much. 3. this was an unexpected side effect, but I noticed how horrible the symbol layout is for programmers on the default swedish layout. colemak symbol layout is much more similiar to the english qwerty which is so much better.

I've done Colemak for 2 years and have switched to Colemak-DH since, which is a rather small change. It is not a problem.

The only problem is that if you also use a non-latin layout, it will do a remapping to the latin one for shortcuts. This latin layout was always qwerty under macOS. So, in the end, I've built with Ukulele a custom layout and that was it.