Interesting to me you say this, as my main criticism of most ergo / split keyboards is they don't have enough keys on the thumb. I started with a Maltron [1] with 8 keys on the thumb and that seems a good arrangement to me.
I was at University, doing a lot of typing, and complained about wrist pain. The IT dudes pulled this dusty old Maltron out of storage and gave it to me. Once I got used to it, I loved it, and Uni let me keep it when I left. I unfortunately had to stop using it because it had a PS/2 connector, everything was moving to USB, and I couldn't afford a new one at the time. I'm hoping my current keyboard (MS Natural) will finally die so I can justify getting a new one.
I haven't used a Kinesis, so can't compare to it (though Kinesis is supposed to have copied their design, so I guess it's very similar.)
I agree, I think the kyria, lily58 (and its derivative lotus58) are decent options, though the BFO9000 could also work as the ultimate split keyboard haha
Given the thumbs limited movement, I came to a conclusion that 2 keys are comfortably reachable, but to reach the third thumb key, the thumb needs to get into a weird and uncomfortable position. That was my problem with the corne I had and I just stopped using the innermost thumb key because of that. Do you have a similar experience?
That is why I have those for keys I rarely use, such as 'esc' and 'del'. Relatively rare - as they are obviously used frequently enough but not really when typing.
And then I hit them with my middle finger instead, or rather smash them as it requires the whole hand to move slightly.
So in my case does not affect speed or comfort (not a frequent VIM user etc)
But if I only had two thumb buttons I would be ok.
Thumb tuck is awful, and is one of my biggest complaints with Corne-style keyboards. I’m building a Dasbob in the hopes that the thumb arc is more comfortable, but we’ll see.
I started my ergo-keyboard journey with a corne. I ended up having issues with the thumb cluster positioning and built my own prototype on new years eve this/last year. That board features four thumb keys, six columns, with four rows for index and middle finger and five for ring finger and pinky (essentially a 6x5 board with four of the bottom keys moved into a thumb cluster. A lot of keys ended up unused on that design (the lowest pinkey and ring finger keys were completely useless).
A couple of months back I built another prototype, this time with a 6x4 + 4 layout. I'm still not loving the layout, four keys is too much for the thumb cluster and I'm looking at dropping down to three. Ironically I've already setup my layout so it almost only uses 6x3 + 3 (I use the top row for non-typing keys like F1-F12), and in effect reinvented the Corne that I started out with...
My Mitosis layout has 8-button thumb clusters but only three on each hand are used frequently as thumb keys. On the other hand, they're set up in my layout so two on each side can be held simultaneously for shift+num layer.
The rest I just use for miscellaneous other uses, like pgup/pgdn and inverted-T arrow keys. It's not for use with the thumb, but it's just a handy place to put keys you'd have to move your hand for anyway.
MacBook keyboards have a similar modifier layout to a Space Cadet in some ways: On your left hand, there’s {Cmd, Opt, Ctrl, Fn} in a row. Emacs on MacOS can use all four modifiers, e.g. mapping them to the historical {Ctrl, Meta, Super, Hyper} keys that were in the same place on a Space Cadet.
Note that this is slightly different from PC keyboards. On Mac, Fn as a modifier is handled by the OS and can be remapped (in System Settings or by individual apps like Emacs). On most PC keyboards, Fn causes different signals to be sent to the OS, making it very hard to use it for other purposes than intended.
I have the moon lander and have settled to almost never using anything on the thumb cluster. It just didn’t feel very natural to me to have to reach for the thumb. I have larger hands too. I think what I do have mapped is only the first two keys too.
[1]: https://www.maltron.com/store/p11/Maltron_L89_dual_hand_full...