I'm currently a DTivo subscriber looking to possibly switch to a Tivo HD. My question is, if I sign up for a 2(or 3) year commitment, and decide I want to upgrade to a newer model, can I keep my contract when switching to the new model, and transfer the service to the other Tivo(deactivating service on the old Tivo)? I ask because I am set on Tivo. I love the interface, and I don't think anything can compete. However, I don't want to be stuck with a single box for 2(or 3) years. I want to be able to buy a new one, sell the old one, and keep my contract the same. Is this doable?