That was discussed with Wojciech and it looks like it is not so common to have longer conversation over PM with some MUC occupant and having "many convesation types" (we already have Chat/Room/Channel and we would need add RoomPM) is complicated to have (separate UI and complicated logic) and actually not so useful.

In the end we concluded that having better indication of what is private message and that we are entering a message to send as a PM.

As we no longer need support for many chats with the same bare JID, I'm going to "revert" some changes as current state is suboptimal and creates more issues than it solves.