I did some layman's research on the web and emailed with an engineer at Clear Channel radio about HD radio issues (let me know if anyone wants me to post his reply). I'll spare us all the details, but, the bottom line is that HD radio is still in a fledgling state and the quality depends on the broadcast signal strength and the quality of the radio receiver. Also, it seems that stations are NOT putting much power into those secondary and tertiary HD broadcasts (HD2 & HD3), so, they tend to have more of the problems we are posting about on this board.
For ICHIBANS, go into your Radio settings and turn HD to OFF, so, you will only get the analog signal. If it was already off and you had problems then it's a trip to Audi service for a test that may yield no results ("Nope, sorry sir, everything checked out fine! You're SOL."). Anyway, if you experienced those problems on and HD broadcast they may dissappear. The problems you describe often occur on HD broadcasts when the signals fade in and out and the radio automatically tries to deal with the problem. If an HD signal is weak enough the radio will even automatically switch between analog and HD causing all kinds of balance issues.
The Left/Right channel issue will be more apparent on songs with strong use of left and right stereo effects. A classic rock station in Dallas (92.5) always plays The Who's "Won't Get Fooled Again" which is one of these strong L/R songs. In HD, the organ at the first of the song that sounds like a British siren is barely audible and makes the song sound "echo-ie", but, if I switch the HD OFF the organ comes through fine and the song sounds normal.
So, try HD OFF.