I frequent 2 dealerships and for both places, they change motor oil from extracting the motor oil from the top.
I am curious. I understand that for w209, there is a drain hole in the bottom. Isn't it more beneficial to let the old oil to fall out by the drain hole? This way, all the accumulated sludge and deposits will be drained out as well.
It is useless to attend this topic, it has been discussed over and over again and it is obvious that people have different opinions and don't want to change, no matter what evidence is given (I'm sure someone blames me with these same words).
As Kajtek1 says, some cars have been designed for oil change via siphoning, some are not, MBs are (with very few exceptions). In this case there is no real difference between the method regarding residual oil in the pan.
If you see how the used oil looks like when you drain it (or siphon, easier to see from a can when draining oil), you realise there is no sludge (if you find any sludge, you have something seriously wrong and draining the oil is not the solution).
Also if you look carefully how the workshops siphon oil, they do not use a narrow tube to the bottom of the pan but a big one attached to the top of the dipstick tube (you cannot do this unless the car has been designed for it). The oil flow is at least the same as it is from draining, so there is no difference if one assumes that the bottom of the pan has some sludge and that comes away when the oil flows rapidly.
Nothing wrong with draining the oil either, it just takes more time and you get hands and clothes dirty.