I use a suction device similar to the Topsider to change the oil in my boat engines. Given the way the pipe lays into the oil pan, I've never felt that I was getting all the oil out. Having changed many an oil from beneath the car, I'd say there is no comparison. I like Larry Bible's overnight method...going the whole weekend, especially long after the engine & oil have cooled, strikes me as fanatical (Larry's self-description)...but who's to argue with that kind of engine life.
'87 560 SL