I don't know of any, but this looks awesome.
How long has strfry supported this?
Are there any clients (or relays) that use negentropy to fetch events more efficiently from strfry relays? How annoying is it to detect support or fall back to regular REQs?
https://github.com/hoytech/strfry/blob/master/docs/negentropy.md
Discussion
A long, long time. December maybe? I don't know if there's anything in the NIP 11 document, that's sort of what I was asking