I have been using Colemak exclusively for five years. I would have never thought that it could lead me into a deep rabbit hole of ergonomics, starting with a mere layout change and ending with heavily customised neovim on Arch Linux, armed with CAWS & Extend. Yet here I am, grateful for that rabbit hole.
Overview
I began with using vanilla Colemak and hacked QWERTY binds for Czech symbols. I dismissed the idea of further modifications and thought of them as utterly ludicrous; I was young and concerned with typing speed only, not realising that those ergonomic enhancements significantly improve workflow beyond just the typing speed.
Near the end of the second year, I tested DreymaR's EPKL and was genuinely impressed by it. I didn't switch to it immediately, but it remained in my mind. I read a little about the divine BigBag occasionally. It didn't take long until I stumbled upon Extend and felt its power. The ability to skip and delete entire words while staying on the homerow amazed me as I've always found reaching for the control key and backspace rather uncomfortable.
Three years and a half in, I was convinced to try Colemak-DH, another modification I used to deem weird. It took only three weeks to gain all the previous speed, and now, looking back, I find it bizarre that I had never stopped to think about the excessive horizontal movements from the D and H positions on vanilla Colemak. At that point, I was much more open to ergonomic improvements, even at the cost of minor relearning; it took only a few weeks to switch over to Colemak-CAWS.
I still use Colemak-CAWS with Extend, yet the tools are different. On Windows, I had to perform various hacks to have shift on the Alt keys, to painfully change shortcuts in apps, and so on; it wasn't a pleasant experience. I exchanged Windows for Arch Linux and switched from various text editors & IDEs to neovim and tiling window managers where I can customise keybinds as I see fit. It's also simple to maintain backups for config files via git.
Current thoughts
I'm satisfied with the setup I have now. It's comfortable. Navigating around in code/files/whatever is blazingly fast. Considering how much more text I'm going to type, I think the effort will pay off soon. Also, the few months of learning "inconvenience" amounted to a lot of new knowledge.
Do I think this is the best setup I could possibly have? No! Quite far from it! That would be my younger self talking. To give concrete examples, I'm still using a pesky ANSI keyboard instead of the ergonomic alternatives, whether tented column-staggered keyboards or something like Dactyl Manuform. Many of the shortcuts I use could be better. Of course, there may be significantly better layouts that I don't know. I think the input method to begin with is inefficient! I expect to see substantial leaps in input methods in the future that will put our current notion of what is ergonomic to shame. That said, I've had enough of relearning to last me a few years for now.
I remain convinced that no quantity of ergonomic tweaks can replace restricting unergonomic activities in the first place. You could be using a non-euclidean keyboard, yet that will not change the fact that you're straining your fingers from constant movement. Nonetheless, there is work to do, and our entertainment forms may require a decent load of keyboard usage, so we ought to embrace that fact.
Using other computers
I'm not fortunate enough to have a programmable keyboard yet; working on other computers may be a complete terror. However, I'm very adamant about being able to use my preferred layout; I have yet to see EPKL being dismissed, even after five years. It's more likely to be a hassle when using others' computers momentarily, like when fixing a friend's or a relative's system or helping a friend with a piece of code because I'm unlikely to be carrying my EPKL stick at that time. Perhaps I should have it with me at all times?
Colemak led me into bizarre places and a weird community of nerds and geeks, and it was worth every penny. I owe a debt of gratitude to many members.