I'll chime in and say: Support for IPv6. It's ... self evident? I think we've reached a point that it's okay to call out a network client that doesn't support it.
I am not sure I understand. How is it self-evident? Is there a benefit over using mosh over IPv4? Performance, stability,anything else? Does it add anything to what mosh can do over IPv4. Is the benefit from the client end or the server end or in-between.