My iPhone4 is having some issues, and while I sort it out I might need to revert to my old 3G. Besides the SIM adaptor (which seems easy to make) is there anything I need to be concerned about swapping the SIM from the 4 back to the 3G? I'm out of contract now from AT&T, and don't want to lose the unlimited data plan that I still have. Don't want to rock the boat and lose it by accident! If I just plug the sim (with adaptor) from my 4 into my 3G will I be good to go? Thanks in advance!