"House", recorded 11:00 pm June 3: I've watched 35 minutes of the episode, and have had over a dozen digital audio dropouts so far. But these have all been what I call "soft" dropouts (dropout does not recur upon repeated playback of the segment, so appears to be in playback, not recording).
Compared with "Damages", recorded 10:00 pm May 12: plagued with many, many dropouts, both "soft" and "hard" (audio packets actually missing from the AC3 stream, so dropouts repeat upon replaying). Some of the "hard" dropouts seemed to be preceded by a very brief buzz or oscillation, probably as the digital stream was interrupted.
So, it looks to me like the CanWest folks found the cause of the "hard" dropouts, and now Showcase digital audio is on a par with most of the other HD stations. Since there have been complaints about Dolby Digital dropouts on the ExpressVu HD channels in several threads in multiple forums, I believe that there is either a software or hardware problem in the receivers.
/ashtonp