Derek,
We don't use agent-to-agent nor the user chats.
Agent-to-agent: we do not "live and breathe" in SmarterTrack, it is just a tool that helps us manage one of the sides of our business - customer service. There are many other tools we use, so most of the time our ST use is "reactive" - we open ST when receive an email notification (we have them for new ticket/reply, comment, etc). We find it more efficient for us to use Comments within the tickets - they are not visible to anyone but the agents, we have email notifications configured for comments, and they are right there in the ticket thread for us to review whenever we need.
User chat: we tried to set these up a couple of times but were not able to get them to work. So we have given up - it was not worth spending more that a day or two for a user chat popup. Yes, we have read through all ST KB articles we could find on the chat setup.
Thanks!