Don't assume that today's SQ will be typical.
During times of change, you often see degredation. Bitrates, I believe are dynamic, and allocated as needed. I have a theory, that during channel changes, they need to allocate every single channel.
Right now you listening to what it would sound like if every single sports channel was being used for play by play.
If I am right, once all of the updates are done, you'll see the dynamic allocation change. It might sound flat on a Sunday when there are 20 NFL broadcasts plus a bunch of basketball and hockey games, but it'll sound better again on Monday.
The overall number of Music and Talk channels is roughly the same before and after the update, so I think you'll see the "normal" sound quality back in the near future. The longest I ever heard the "muddy" SQ was a couple of weeks.