I held a number of online conferences a few years ago. The attendance sweet spot was 5-15~ just using zoom. Under 5 is just not enough people. Beyond 15 it's very difficult to talk naturally. Becomes more of a consumption only medium. I hadn't tried having dedicated chats for different talks before.
I'm looking forward to doing it on zulip instead. Having unread counts per thread should make it much easier for speakers to keep track of which questions they haven't answered yet.
As someone who has recently started using Zulip I'm really excited you made that call. Its topic model really is unreasonably effective at improving the whole chat experience.
