// This is the best we can do right now: in an imminent
            // spec version we should define a different D-Bus error name
            // for each ConnectionStatusReason

This has now been done.

Also, ConnectionStatusReasonNameInUse now maps to either AlreadyConnected or ConnectionReplaced, depending on previous state, and not NotYours.

Also also, Connection should bind to the ConnectionError signal, for notification of specific D-Bus errors from CMs that support it (Gabble should use this to signal RegistrationExists, although it doesn't yet).