For those with DSG boxes, the prevailing wisdom is that the vehicle must be perfectly level for all drain-outs, regardless of refill method. This seems to follow the particular concern regarding the fluid level sensitivity of these boxes (+/- .2L tolerance, and factory procedure snorkel-based fill and temperature level adjustments). DIY owners typically jack all four corners for the DSG service without question for fear of somehow offending the DSG gods.
As I found zero information elsewhere where top-fills are performed (including all the VW/Audi fora), I will post this here, for the VAG/DSG world at large:
For top-fill DSG fluid changes, you do NOT need to keep the vehicle level. Ramping up the front end (within reason) should allow a full and exact factory drain-out.
We did one yesterday on a set of standard height front ramps. Exactly 4.5L drained out. Refilled with 4.6L from the top (+0.1L for filter), slapped on a new filter, re-calibrated the box with VAG-COM, and it shifts beautifully.