

Slrpnk hosts an XMPP/Jabber for our users, mods and admins to communicate. Its worked pretty darn well for the past couple years, with very low resource needs.
The clients are pretty slick now too, such as Cheogram or Monocles for mobile, and movim is an excellent web app with support for group calls.
I’d certainly recommend it over Matrix/element.
I’m afraid that’s quite outside my field of expertise. I can only report how my experience on XMPP has been as a user, though perhaps @poVoq@slrpnk.net, who hosts it, may be able to weigh in on that. Edit: ah, I see you already have 😄
Though from my untrained eye, it seems that Jabber.ru was compromised due to not enabling a particular feature on their server
And it seems that hosting it externally on paid hosting service (hetzner and linode) left them particularly vulnerable to this attack, and tgat it could’ve been mitigated by self hosting the XMPP locally, as well as activating that feature.