Hmm, never heard of any issues with RadioShack, but I have never gone through them, and only been in one literally 3 times my entire life lol. Surely you can call and ask about their methods to find out though.
I manage a radioshack. Our upgrade process is the same as everyone else. We have an optional trade in program. Some like it some don't. We also don't deal with mail in rebates. Stop in to your local radioshack and check out the nice deal we will be offering on the one x for pre order.