I had given up on this issue but recently discovered TSB 21-004-13 and had it applied today. It seems to have worked. I could consistently replicate the noise at 7mph prior to the update. Today in stop and go traffic (5-10mph) everything was smooth.
The downside is that it did cost $57.50 to have it applied. The first thing the dealer rep asked when I asked to have it applied is if someone had quoted me a price. Since the TSB is for vehicles built prior to May 2011, most are past the 3 year/36,000 mile bumper to bumper warranty. Even though it is a power train issue, the 5 year/100,000 mile power train warranty only applies to mechanical issues. IMO it was worth the cost to resolve the issue. I am just glad the fix does not involve tearing apart the drivetrain.