Just register the used system under your account like people do nowadays when transfering xbla licenses from one 360 to another if u upgraded hardware. Think about? They know the bulk of people that by revisioned hardware when it first arrives are mainly current system owners wanting to upgrade so why would they not allow the user to sell their old version?
How our favorite systems are just like humans and sometimes have issues finding their special someone...
Xbox 360 wants to Kinect & PS3 wants to Move! Why are both systems having such relationship problems? The reason is they both become so infactuated with desire while watching the Wii as it waggles on by. They simply want what they can't have.