I have this keyboard for a bit more then week, so a bit too early for any thorough review.
Anyway, I think I already have something to share. Some background first: I'm professional programmer for 30 years. Mostly using Emacs editor for my daily work. I've already had few RSI episodes, but recently it got worse: pain in my finger joints and metacarpus.
So I started to look for solution. I thought about something like Microsoft or Logitech ergonomic keyboards, but I gave up for two reasons: first, having some experience with mechanical switches I did not want membrane any more. Second: my biggest problem with regular keyboard is Crtl key, which is located as it was the least-used one, not almost-the-most... And those two models do not change anything about it.
Keyboards like EgroDox or Dygma scared me: both with price and with learning curve, which I was afraid to be close to vertical.
I tried 3 various mechanical keyboards in various layouts - but still non-ergo. The fatigue from typing was surely smaller, but, well, I expected something more.
Then, I decided to try x-bows. The selling point for me was Ctrl key placed in the middle. And the fact, that the rest of the layout looked pretty familiar.
First day... ohhhh.... it was a little nightmare... I was mistyping every single word. Typing speed dropped from something like 40-50 to maybe 15.
But this was exactly what I expected. Besides, Ctrl under thumb was such a relief...
In maybe 3 days it was much better, but still slower than before. I need to use typing-tutors to reprogram my muscle-memory.But it gets better with every day. After a week I'm back at 40-50 wpm, but still mistyping more often than I would like to. I expect I will manage to make it better with more practice.
BUT, most important thing is that I'm much better with my RSI aliment. Pain in finger joints is gone. Pains in metacarpus: much smaller and the tendency continues.
Most visible result is my left pointing finger: for a long time, I was not able to bend it to the full extent (relative to the same finger on my right hand). Now I still cannot, but the range I can bend it has significantly grown (50% maybe). I wish I did not make any pictures before, but I did not expect such significant change. Maybe red switches, which are so light to press have something to do with it. But I'm pretty sure it is not only that. Entire layout causes less fatigue when typing. The enter and backspace keys in the middle is something I like very much - despite it takes a while (a decent while...) to get used to it.
This is the most important point. Now some "less important". Build quality is excellent in my opinion. Let's hope it will be as durable as it seems to be. Key-caps are ABS, but it feels much better under your fingers than other ABS key-caps I've tried, e.g. from Keychron. No sticky, rubber-like feeling. I don't like keycaps fonts, but it has absolutely no importance for me - I touch-type: don't have to look at them.. ;)
I do like they left dedicated function-keys row and that function keys are in groups separated by small gap - like in traditional keyboard.
This keyboard has no dedicated Home and End keys. Some people seem not to notice it before purchase. For me it was not a big problem: the keyboard has QMK firmware, so you can remap keys to have home/end anywhere you want (default is F+PgUp/Down).
Besides in Emacs I'm used to use other key-combination for home/end. But for some people it may be a real pain in adaptation phase.
If you consider buying it, you must be aware that this keyboard is, by design, a compromise between ergonomic and traditional layout. For me it seems to work: it is traditional enough not to make me throw it away after 1 day fight and ergonomic enough to give visible results.
I need few more weeks to be sure, but right now I think I will not get back to traditional skewed-keyboards any more.