An important part of this equation was touched on but not explored, and that is the oilpan design.
If by design, the low spot of the pan is where the dipstick goes ( and therefore the topsider tube), then this would lead to the fact of getting more oil out (all else being equal, like oil temp at change and going back and getting those last few ounces) with the topsider.
If however, the drain plug is the low spot, then you will most likely get more oil out by removing the plug.
I have not seen all of the MB oil pans so I cannot commnet on what model has what. I know that most North American engines have the drain plug as the low spot, and usually by a fair margin.
If by design, MB has dcided that they will use a topsider method, then they may very well have made the oilpan to accomodate properly.
Just a thought.