Now that we've had a cooling off period 
what do we think?
It seems to me most people have drifted back to IRC. Gitter activity is low. Many Plone Slack users have gone "inactive".
I think we need to focus on two needs:
- what do newcomers need, not specifically for chat, but really for these separate things:
- asking questions and getting answers
- meeting with and interacting with the community
- what do current community members need
For newcomers, if they need to ask questions and get answers then IRC is not good since it's hit or miss if anyone will answer before the newcomer disconnects.
Currently at http://plone.org/support we already show an emphasis on "asking questions" (goes to stackoverflow) over "chat" (goes to IRC).
Maybe for the "chat" bit we should emphasize there that people should stay connected – and how to do that – and maybe how to ask questions (don't get me started on that!) because they don't seem to be reading the page that is in the #plone channel topic.
For questions, we should consider how to mention this forum better (it's not mentioned on that http://plone.org/support page except in a teeny tiny footer!). It may be hard for a newcomer to decide what has long-run value and what doesn't so they'll need guidance.
I think with that we really have addressed what newcomers need. And then we can discuss further what current community members need and/or want.