...Stupid me, I should have taken Carson's (Riverside Audi) advice and initially purchased a new ignition control unit (sometimes called an Ignition Amplifier or Power Stage Output Module), rather than spending the money and time installing new coilpacks. There is so much commentary on the coilpacks that I just assumed they were the problem. But, as is mentioned elsewhere, the coilpack on the 2002 AR 2.7T is solid.

You can determine if an ignition control unit is bad by exchanging the two identical modules mounted next to each other (on top of the air intake/ filter housing...just pull off the plastic cover to see the two parts). If the problem cylinder changes from one bank to the other ("123" to "456" or vice versa) then the ignition control unit is bad...not a coil pack. I scanned the running engine with VAG-COM and could actually see the misfires change banks when the ignition control modules were exchanged.
I determined which control unit was defective by swapping out each control unit with one from my 2000 A6 2.7T. When the bad control unit was placed on the A6, that vehicle now had the misfires. (You can also look at the color of the connectors for each ignition control module. One connector pair is black; one pair is pinkish brown. The repair manual says which color goes to which bank...you'll have to look this up.)

Problem solved. Well, I had to buy a new ignition module. It takes 10 minutes to change it. You'll need to clean off dirt and debris from the heat sink mounting location for the ignition module. And you'll need to use some new heat sink paste to allow heat to transfer from the module to the heat sink. This paste might come in a little plastic squeeze pouch with your new module.

BERU also makes a ignition control unit...not just Bosch.