I still haven't figured out the hierarchical channel structure/channel linking.

The use case I had was if I wanted teamchat/allchat done via different hotkeys, like if I were playing with some friends on an RTS and wanted to talk crap on all while strategizing on team.

Edit: my two cents: I've been running Mumble for a long time, and though it isn't as multi-tooled as TS, I love its simplicity and its quality.