For example, someone will change the Mac's sound IO for whatever reason, then the Hangout audio IO will change and someone else won't realize this (e.g. sound comes out of the Mini speaker in the closet, instead of the speakerphone). So a few mins at the start of every few meetings is spent debugging these things.
The holy grail everyone wants is, "walk into the room, and it just does the right thing." This looks like a step in that direction from our current setup.
The Chromebox is bound to a room (GApps resource) so it is aware of which meetings start when, and shows this to you on the screen.
Also, the Mac Mini solution involves creating named GApps accounts, and inevitably those sessions time out or people log them out. These devices also solve that problem (they are 'bound' to your GApps domain), which for a company with more than a few conference rooms can get really old.