Last year I pre-ordered the 3gs to upgrade from my 3g. When I got it in I played around with it for a day or two, at my house, then I decided to put it back in the box and wait for the jailbreak to come out. When the jailbreak came out, I completed the switch to the 3gs and sold my 3g. I planned on doing the same thing this year until the antenna issue came up. Now I want to fully test the iP4 at work (which is where 90% of my iPhone use is at) where getting a signal is a challenge sometimes, but I would like to be able to switch back to my 3gs if needed. I don't want to wait to do this as I we only have 30 days to return the phone if we're not satisfied. The big question is what to do about the mini-sim. I assume the sim in my 3gs will be disabled when I activate the iP4. Do I just get one of those mini-sim adapters? Anyone successfully swapping back and forth between your iP4 and another iPhone or any other phone that uses a full-sized sim?