My suggestion is to add a informations panel that could be on right (but could be moved elsewhere).
If we would select a chanel, It would display the informations about de chanel (chanel name, image, description, number of users...)
If we would select an user, It would display the informations about the user (username, avatar, personnal comment, country with a flag)
It wouldn't be too much difficult to implement and It would be very nice.
I hope you will like my idead and that you will implement them.
Mumble is still very good but make it better. :)
Best regards and thank you for all your work !