I greatly respect and appreciate all the work @luceos has done on Byobu (and everything else). But we are finding private discussions don't work as a substitute for private messages.
My members buy and sell a lot of things on my forum, and there is a need to send a private message to negotiate details and shipping info privately. And those messages shouldn't be listed among discussion threads - they are 2 very different things.
Every other forum I know of has this as a core feature. It's just a simple conversation between 2 members. Is anyone considering building a plug-in? @clarkwinkelmann or @luceos perhaps?