Used a Pela on my old VR6, MK4 R32 and Edition 30. Always leaves at least a litre in the sump regardless of marque in my experience. The last time I used it on the ED30, it only pulled 3.5 litres out, despite shoving the hose in further and constant pumping.
I would rather dump the sump and then I know ALL of it is evacuated and not a litre left in there to contaminate the fresh oil.