I have an autocom hard wired under the seat of my BA. You can plug in an mp3 player, pillion or radio for bike to bike. I don't use it much though as pipedr said, I want the relative "quiet".
I used to plug in the mp3 player but found it quite distracting, not concentrating on the road as much as I should.
Though the autocom is good, I don't think I would buy a system again.
Jon