I (barely) noticed a few short audio dropouts during the commercials but it sure didn't bother me nearly as much as the blasting jump in audio level on the (mercifully few) local commercial breaks.
Since someone's raised the subject of dropouts - right now I have a direct HDMI connection from my Scientific Atlanta cable box to my Panasonic 42" plasma. My Pioneer DVD has only component video output, so with only one digital video source there seemed no point in going through the 990. But a few minutes after turning on the Panny and the SA there's always a 2-3 second dropout in both video and audio. Does anybody have an idea what might cause this?