I recently bought a 2004 TT Roadster 3.2 DSG with 55k miles. The PO had a bunch of service records that he got from the original owner, who had purchased a maintenance agreement when he bought the car. Because of the maintenance agreement, the car appeared to be well maintained. The records showed that the DSG service had been completed at 38k miles, but since I like to start with fresh fluids, I decided to change the DSG oil along with everything else. After reading through numerous threads, I decided to do the catch, measure and top fill method.
Once I removed the drain plug, I was a bit shocked to see how much fluid came out prior to removing the stand pipe. I estimate that about a liter or more came out, and once I removed the stand pipe, I collected a total of 5 1/2 liters of fluid. Reviewing the Audi dealer service record, they charged the customer for 6 liters of fluid. So, 20k or so miles driven with the gearbox overfilled.

I refilled the box with 4 1/2 liters of new Pentosin, using the standpipe overflow as a guide and then adding 150 ML to compensate for the filter.

Just a note on the procedure:
The filter is accessible without removing anything other than the filter housing.
This funnel from Amazon (Hopkins 10704 FloTool Spill Saver Measu-Funnel) fits the hole in the filter housing perfectly. The tubing could be longer though.
Warm the oil in the sun. Goes in much more quickly.

I honestly can't see a reason for using the VAGCOM to measure the fluid temperature. The bulk modulus of oil doesn't change enough in the temperature range stated for it to matter much considering the accuracy of the things we're using measure the amount of fluid going back into the transmission.