I am getting ready to do my 80K DSG change this week. I have the Febi-Bilstein oil (5L but I will have a 6th on hand) and the filter and washer.
I am planning to replace the stock filter cover with one of the finned aluminum replacements. It's probably voodoo, but my 2010 Golf MK VI TDI has a Stage 1 Unitronic ECU tune, and doing a little more to reduce the DSG temperature seems reasonable.
The measure/refill makes sense on practical terms, replacing what is removed, but that has to assume a normal amount is being removed, i.e., no leaks or losses beforehand. But if, for example, you drained out only 3.9L, you probably should still plan on putting in 4.6 L in refill (and then look for possible sites where you are losing fluid.) Your old fluid will be cooling and contracting once outside the case, so the only error might be in measuring too warm and replacing with cooler fluid of the same volume which when raised in temperature (and expanded) might give overfill (which you would find out about only by opening the drain plug with the snorkel in place.) So the drained fluid should be measured at the same temperature as the replacement fluid, to make the calculation as error-free as possible. It is not as if the fluid temperature (or difference in temperatures) doesn't matter at all, even though you aren't using the VCDS to measure it.
I was planning on doing the bottom fill method at first, but I can't see how it produces any more exact a replacement of the removed volume of fluid; it is just faster than gravity fill, at the expense of wasting fluid both in filling above the top of the snorkel (which then drops out and is wasted when it warms up) and in the filling apparatus lines. (In a shop, where you might have a drum of oil and compressed air line to pressurize the fill, that oil isn't wasted; in a DIY with a pump sprayer bottle setup, you would want to drain that back into a bottle to save it.) The VAG-COM or VCDS calibration with the snorkel in place to drain out your overfill at the 35-45 C temperature band takes time also. In a shop where the car is being serviced with the OBD connection throughout, VAG-COM is available and there is a time-critical work schedule, wasting a little oil is probably reasonable, expense-wise.