This is the layout I'm using.
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Interesting - but why didn't you put all punctuation and symbols on a single layer? Looks like some symbols need to be shifted - gosh, I do not even remember whether that is standard qwerty behaviour?
Does anyone use a 40% for actual work? It may be useful to know his/her experience.
I do - even though there are still technically more keys present than I use (and even some duplicate assignments on diferent layers) my split daily driver features only 3 rows with 5 keys each plus 3 thumb keys and a few extra mods, so is quite similar to a 40% in terms of size.
I have omitted the function keys as well as some modifiers below, but with 4 layers everything I need for programming and mainly command line work is available with a tuned layout very comfortably on a 40% board.
Once you get used to it, toggle the layers automatically without thinking and can touchtype anything blindly, I'd say it is definitely very usable for everyday work, even more so than larger boards as your fingers do not nearly move as much! Sure, you have to find a smart way to arrange the modifers you often need and combine in firmware, maybe even create a few custom macros if you rely on "Ctrl-Shift-]" or similar combinations, but this is merely an exercise in figuring out what you really need and then re-using some keys with a second mode when pressed together.
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