Someone at a MB forum tried both methods about 8-10 years ago, he done it both way at two oil changes.
One oil change he done extractor first then removed the drain plug, next oil change he done the plug first then did extractor.
There was no oil came out from the drain plug after he done siphoning with his Mityvac. On the second trial, he got few ounces with his Mityvac after he done with the drain plug.
MB dealers use a strong vacuum machine and use the dipstick tube as suction tube, the tube bottoms at the lowest point of the oil pan.
Before I do oil change I check the oil level to see how oil in the sump, the Mityvac always get out at least that much. The capacity of the E430 is 8.5 quarts at max level, if it was 2-3 mm below max then there was only about 8 quarts at time of oil change. The Mityvac got around 8 quarts. I tried this once few years ago, I didn't fill up the sump after siphoned the old oil at night, I siphoned again the next morning and got around 2-3 oz. It was so little so I didn't do it again, and I afraid that I may forget the next day and drive off without oil.