I'm also in the Onyx BOOX camp (Max Lumi, going on my fourth year, numerous previous mentions/discussions in my HN history). Most of the observations on the Daylight Computer, particularly about readability under direct sunlight (the exact opposite of all
other portable devices I've used, save the similarly B&W LCD-based Palm Pilot ... oh, a quarter century ago now) really is quite nice.
Other features seem pretty comparable with the DC. I suspect DC's high-speed refresh beats E-ink, but that E-ink's persistence, resolution, and clarity are strong counterpoints.
The observations on B&W v. colour are interesting, and mostly match my own experience. Coding (in vim under Termux) takes me back to monochrome screen days (though those were largely green/amber rather than B&W), and the loss of colour syntax highlighting can be somewhat jarring (though I remember finding the garishness of it being initially offputting when I'd first begun using it). I find the Web much less distracting in B&W, and only rarely miss colour, though for some data presentation (e.g., graphs and charts) it can be conspicuous by its absence). I'd like to try a colour e-ink device at some point.
For a device that maximises portability, preserves battery life, functions spectacularly in all lighting conditions (though diffuse overhead lighting tends toward glare), and is principally aimed at reading / listening / notetaking, with light technical work (largely under Termux w/ a Bluetooth keyboard) I strongly recommend the form-factor, and would suggest exploring either e-ink or e-paper depending on specific preferences, the key distinction likely being the refresh/persistence aspect noted previously.