I'm not trying to diminish the problem, just to suggest maybe not all the HD channels are doing this all the time.
I've kinda watched this thread since you started it, but even though it's baseball season, and the number and amount of non-baseball channels that impede upon the 99.9% of time that any game is on (okay, there IS time before 7pm EST in my daily schedule, but it's sure much nicer being on the west coast than the east if you don't want to doze off in the easy chair on those west coast games!!!)....
BUT, dropouts occur on every channel, every minute/hour, every game, on all the systems I own.
HR20-700 - through Slimline5 w/WB616 multiswitch,
TOSLINK to Yamaha RX-V3000
H20-100 - through Slimline5 to SWM8, same audio path as HR20-700
(both top units in 'home theater'), may get replaced by
HR24 at some future date (!)
HR20-100 - same route as H20-100, but HDMI to Samsung HDTV
(no surround sound processor, in bedroom)
HR20-100 - 'portable' Slimline5, direct cable to HR, to Samsung HDTV
HDMI through Panasonic amp
(this system in 5th wheel trailer, only occasional use)
If you listen closely, and especially with live baseball, you'll get 'micro-dropouts' even on the HR20-100 direct HDMI to the HDTV set. I'm sure that most folks would not notice it, but I do. Those 'micro' happenings kick both my large (yes, old) Yamaha (I'm taking a collection to get something with TrueHD/DTS-HD-MA!) as well as the newer little Panasonic surround amp in the trailer to 'skip'.
Right now, I'm watching the TB Rays game on SunSports, who do not have Dolby Digital turned on, and so its flat stereo. Still dropouts. Maybe not as many as, say, NESN or YES, but they're there. Consistently.
It's a system-wide problem. And since it occurs even on those channels that are NOT Dolby Digital, it's something that all channels are routed through, and that includes non-HD and non-Dolby types.