I'm mostly typing on Corne keyboards now; a split kit keyboard with 42 keys, so still considered 40%, but fewer keys than most other 40% boards. (so you have to learn to cope with not having dedicated arrow keys, for example)
I can't imagine ever going back to a non-split keyboard; for me, it's a much better typing position to have my hands shoulder-width apart rather than squeezed together. I think that's more important than the "every key is within reach of the home row" argument for the 40% size in particular (although I've kind of fallen in love with the 40% size, but I could cope with going to a larger keyboard again better than I'd cope with going to a non-split, I think)
But more than that, as a programmer, there's something meditative about maintaining the custom hardware I use to do my job. Double-checking the soldering, tuning the firmware, taking it apart to polish the components and then putting it back together again, etc. Reminds me of the Zen of Motorcycle Maintenance, in a lot of ways.
The Corne's predecessor, the Helix, was a significant leap forward from the Let's Split design that inspired it. It had a lot of firsts. First split design with reversible PCB, first split with per-key RGB, first split with OLEDs supported on both sides - necessitating some custom OLED code in QMK that was ahead of it's time. The Helix and it's derivatives (like Corne) represent the apex of 2018's DIY radically designed small boards movement, and the Japanese DIY keyboard movement too.
I'd really like a keyboard with e-ink keycaps, so that they update as I flip between mappings. It'd be particularly useful when swapping between languages / character sets (e.g. Hebrew, Greek, ...)
I'm a huge fan of my Corne (crkbd for those looking it up) also and I agree with everything you've said here.
In fact I'm even thinking of building one with the outer columns chopped off if I can get a bit more used to chording.
It didn't at all take me long to get used to the 40%, the split boards, or the column stagger after using a 60% for years and I was quickly back up to ~100wpm in about a week. This was my first time with the three. Most of all, I'm never going back to a non split if I have a choice.
The original sin here is home row touch typing. I type like I play the piano- my hands move up and down the scale. But split keyboards are an anathema for this.
I can't imagine ever going back to a non-split keyboard; for me, it's a much better typing position to have my hands shoulder-width apart rather than squeezed together. I think that's more important than the "every key is within reach of the home row" argument for the 40% size in particular (although I've kind of fallen in love with the 40% size, but I could cope with going to a larger keyboard again better than I'd cope with going to a non-split, I think)
But more than that, as a programmer, there's something meditative about maintaining the custom hardware I use to do my job. Double-checking the soldering, tuning the firmware, taking it apart to polish the components and then putting it back together again, etc. Reminds me of the Zen of Motorcycle Maintenance, in a lot of ways.