Slack has raised our charges by $195k per year

Do you mind me asking if you'll be self hosting mattermost? If so they're moving to a 1000 User hard limit for self hosted instances. https://forum.mattermost.com/t/solved-is-there-any-limitatio...

That discussion also mentions: "Framasoft is maintaining a soft fork called Mostlymatter that removes the arbitrary user limits"

Yes, I mean they are not difficult to remove, but I think it would be fair to add the context that they're going to have to fork it. E.g open source is not a panacea either, they will likely also struggle with postgres being a bottleneck for that number of users (particularly on search), the redis integration is not part of open core.

It also looks like that specific fork hasn't been touched since may 2024 ? https://framagit.org/framasoft/framateam/mostlymatter -- so realistically they may need to maintain their own fork.