1) Bluetooth

2) Multi-device support/switching (3 minimum)

3) Wired-use operation as a backup

4) Mechanical switches

BUT ALSO:

5) Not to have to give a shit about my keyboard, or spend much time on it, and ideally not spend much money, either

I settled on a Keychron and it's been really good for my purposes. It's a solid keyboard for someone who wants an entirely OK mechanical keyboard for non-bank-breaking prices.

I have had exactly two problems with it, one resolved:

1) It liked to "go to sleep" way too fast, then took 3-5 seconds to wake up and reconnect. A quick look at the manual showed me how to turn that off with some magic key combos. It lasts days on a charge regardless, so it was purely an annoyance. Anyway, that's resolved.

2) The stupid l33t g4m3r d00d light patterns it can do. This was one of the most subdued mechanical keyboards I could find (WHY do so many have this crap?!), and it still has this damn "feature". You can set it to steady, low, always-on light, which is the only thing I ever want, but there's a button at the top right corner that's easy to brush by accident which causes it to cycle to the next light pattern. You then have to hit it like 20 times to get back to "stop trying to look like fucking Las Vegas" mode. I'd have paid an extra $10 to not have this "feature". Just remove the whole damn thing, set it permanently to steady-light, and keep the dim/bright keys for it only (which can also be used to turn it to zero, so, off). I manage to screw this up about once every couple weeks. It's annoying, but not enough to get me to buy a different, probably more expensive, keyboard.

(seriously, though, thanks for the tip)

Edit: It's not in the K2 manual but there is a shortcut, FN + L + lightbulb key that works to lock it -

https://www.keychron.com/pages/k2-user-manual

https://keychronsupport.zendesk.com/hc/en-us/articles/360052...

Now, it's my ideal keyboard

The stock keycaps are nice enough but I replaced mine with the Drop MT3 Dasher caps only because I'm a crusty old ex-Data General engineer looking for a nostalgia kick :).

All in all it's a real nice keyboard. It's also absolutely solid in construction with a metal frame and you could easily do someone quite serious (defensive) GBH with it.

I'm not sure why anyone would buy the Logitech in question, not being able to swap key switches these days on a $100+ keyboard seems a bit mean, and was a bit of a deal breaker for me when hunting down what is my first customisable mechanical keyboard.

I should also add that mechanical keyboards are in no way a hobby thing for me and I certainly won't be spending hours on end on customisations other than the odd key switch experiment.

You wouldn't happen to know another wireless keyboard with the same layout as the K4, by any chance? It's also ok if it's missing the arrow keys, I just want a keyboard with the numpad but without the Insert/arrow keys block.