Ha, I love these stories of reps flexing their power trying to tell people what they can, and cannot do. I'm pretty sure you can switch **** out, and return it, or whatever, as much as you like during that 30 day period. Sure, it can be obnoxious, especially since the phone can't be sold. But you can do what you want as long as it is reasonable to some degree.
I sold my EVO4G on ebay a month out (because I wanted top dollar). Then I bought the EVO Shift 4G, but I realized that if I am going to have a device to try out for a month, I might as well get something different, so I returned that and bought the NS4G. Then when my 3D came out, I returned the NS4G and bought the 3D. I felt a little guilty..but w.e, and if anyone tried to say anything, I could have just flat out returned it, and then go to another location.