I've had my TiVo Roamio for two weeks. I record exclusively OTA. In general, I've been pleased with the Roamio. Only...
Once in a while (twice in the two weeks I've had it) I'll be watching a show I recorded and the audio will stop for several seconds. The picture displays flawlessly. When the audio resumes, it is in sync with the picture. This will continue to happen a dozen or more times throughout a half hour show.
If I replay the show, I'll get dropouts of different duration in different places than the first time I watched. Sometimes the video will very briefly also go black.
If I restart the TiVo, the show plays flawlessly from beginning to end. This is not an input problem, as the recording is clearly fine after restart.
I've read about odd behavior with Roamios and HDMI outputs. Mine is a fairly simple setup; the Roamio is connected via an HDMI cable to the TV - no intermediate home theater box, etc.
I've also never seen this problem with live TV through the Roamio.