I've never done a (successful) post production matrix, but the many I've done on the fly usually float from 80/20 to 60/40 SBD/AUD, depending on the situation like everyone says. However, I normally have a good amount of control over the SBD feed, so I can mix and pan the instruments where I want, and I normally just run two mics off the lip of the stage to "mic the crowd" so to speak. It sounds more like the live releases that people purchase in stores, and the band I work for prefers that. (I dig it too, but then, my mics are not the greatest....)