The A300-600R maintains a rather tail heavy configuration (around 37% MAC I belive) in the cruise by transferring fuel to the tailtank. The MD-11 can burn fuel off the tail-tank at a ration of 1:7.5 lbs with the centre (aux?) tank, which maintains a tailheavy configuration without going out of trim. The MD11 will pump around the fuel during descent to arrive at a somewhat neutral (25%ish MAC) in time for landing. Or some sorts black magic
Forgot to add; yes tailheavy is beautiful ;-) Less trimforce = less drag = reduced fuelburn.