Actually, for the Mercedes, the "traditional gravity drain" isn't traditional. Mercedes has designed their engines for dip-stick drain at least since my 1980 280E and probably earlier. All Mercedes dealers use the dip-stick suction method when they service Mercedes and have since at least 1980. Every independent MB mechanic I've ever seen uses the dip-stick drain method.

(P.S. it doesn't matter to me which method you use, but don't choose the drain-plug because it's "traditional.")