I guess I wouldn't be too worried about getting a refurb. The one component that I would be concerned about is the HD, which would almost certainly be replaced when a unit is refurbished. However, backing up anything you've recorded that you want to save to the external HD is a good idea.
If you threaten to leave, they're likely to offer you lots of stuff to get you to agree to a new 2-year contract (I couldn't believe all the stuff DirecTV offered me; almost enough to get me to stay). If you're really willing to leave, that's probably the best approach.
By the way, I would...