@yawnbox stable with a legacy caveat.
The ultimate goal is to introduce a new groups protocol that augments the untrusted services model with p2p exchanges "hybrid groups" - while we don't anticipate any significant changes to the cwtch server to support that work, that may change as research progresses.
The standalone server has a few small features that built-in server hosting doesn't, but we are planning on aligning both in a future release.