Here is what I think. If one is a Showstopper and one is a Replytv branded unit, I would keep the Replaytv branded one. Why? Because the Replaytv branded one may have a premium associated with it if you ever want to try to transfer the service (if this is even still possible). I have heard that it is easier to transfer the activation if it is a Replaytv branded unit.
Just my 2cents.
Just my 2cents.