Can Tox do persistent group text chats with offline message delivery to people when they sign in again? It's the one killer feature of Skype that keeps me on it. No open messaging programs ever support this it seems like.
I have to echo the parent though, getting history from the period you were disconnected is a killer feature of skype that seems to get little or no attention.
It is one of the major things that keeps some of my group chats on skype.