The moderation team is aware of the pain folks are having with Slack as we grow. We’re currently investigating Zulip. If it gets far enough along we will put out a call for testing. 
I’m currently moving this forward. The most helpful thing I could get from folks on this right now is experience reports like the following:
- I tried Zulip in such-and-such a context, and liked / didn’t like it because such-and-such a thing
- I have participated in an open source project that uses Zulip, and this is how it helped or hurt the project
I’m especially interested in ways you’ve noticed conversations flow—is “topics for everything” a big barrier to entry to discussion? Do you feel OK jumping into conversation? Have you felt pressure to respond, or been able to get help in the ways you needed when you’ve used Zulip?
These would be especially helpful reports if your experience was with a very large Zulip instance. I’ve already talked to several Recursers and it seems nice! But more feedback would still be helpful, especially from folks at RC.
For what it’s worth, I don’t currently see us importing the full Slack history into a Zulip instance. Zulip seems to be just different enough that the character of interactions would change pretty significantly. We did the same thing for our Google Groups to Discourse transition, and that worked fine. I know it’s not 100% the same thing, but I think it’s better to start this slowly and grow.
Finally, on the off chance that any of you have registered the “elm” instance on zulipchat.com, please get in touch. We have a good enough name for testing but would like to make it unambiguous.