I'm a bit disappointed in that response, Larry. You waved your hands and dismissed everything, but didn't offer any rationale, logic, or evidence to support your points. I'm afraid that despite your guru status in this forum, I don't find unsupported arguments very convincing.
I've used both the drain plug and topside methods on several of my mercedes - 123, 124, and 210 chassis models. After using the topside method, I've had to add noticably more oil to bring them up to the full mark vs. using the drain plug method. Hence I contend that the topside approach is quite thorough. My experience, empirically determined, I might add, is that it certainly removes more oil than draining for 20 - 30 minutes.
Have you ever determined the additional benefit of your overnight drain versus, say, 20 minutes? How much additional oil is removed in that extra 12 hours?