Wound up going with a #Razer Basilisk V3, let's see how it works!

In the end I had narrowed it down to a few #Roccat and Razer models, and it seemed to be a bit of a theme of the reviews on NewEgg that people who had tried both preferred the Roccat ones by a smidge. (I have also been happy with my Roccat mouse for a long time.) But all things considered they seemed very close.

One of the tiebreakers that tipped me toward Razer is that the open-source project that provides Linux drivers and tooling for Razer devices has a nice welcoming and easy-to-navigate website (https://openrazer.github.io/), while the equivalent project for Roccat has a website (https://roccat.sourceforge.net/) that, stylistically, looks 25 years old and with a quarter of the FAQ devoted to childish mocking of people's questions. (To be fair those questions *are* somewhat entitled, but still, it's an offputting response.)