Very helpful info in this thread, and I wonder if it relates to a problem my wife has with the OEM XM in her '08 Nissan Pathfinder, which we purchased used about a year ago.
Her reception is noticeable worse on one channel (RadioClassics, channel 82) than other channels. On 82, she'll encounter drop outs or total reception loss in areas where other channels come in fine. Switching to another channel typically works fine, and even switching back to 82 sometimes seems to restore reception (even while the truck is stationary).
I assume XM reduces the bits/channel of 82 more than other stations since it's not a high quality original source and realize this reduces audio quality, but hadn't thought about reception. If I understand post above correctly, fewer bits/channel can reduce reception?