FCP.CO has a video by Micha Schmidt on using Roles, and getting out the audio to do a mix.
It is worth checking out, and makes it seem pretty useless as the exports using ROLES for audio tracks, only gives you complete mixdowns of each track that has been assigned Roles, but they are mixdowns, and not at all OMF tracks with individual audio tracks. So not all that useful. Sure you could make versions with audio on different tracks like this (if you have another program to make tapes).
My question do Roles export with Automatic Duck Pro Export 5.0 so that the clips show up in tracks? If that works, then it makes Pro Export more useful, but if not, Roles are pretty useless.