This is pretty much exactly what we want too for the same reasons. Rather than replacing Zendesk we would be replacing Tender with Discourse.
Discourse would be ideal except.
- TL0 users can’t send PM’s (even to blessed groups).
- It’s not super obvious how users can send PM’s to groups of users (ie, staff).
Another suggestion I posted elsewhere was a the idea of a category where TL0 users can post (and see their own topics) but only members of a blessed group could see and respond to all topics in that category.
Update: So after doing more digging, I noticed that new users can have a trust level higher than TL0 by default. This solves the problem of not being able to send private messages after sign-up. Though it does remove some of the newbie abuse barriers.
The group PM feature is still not very obvious. One thing that would make it easier would be if there was a way of embedding an link in a topic that opens the PM composer addressed to a group.