I have a question for everyone. I decided to not port my sprint number yet and take the 3G iPhone for a 30 test run. I purchased the 8GB but now I think I want to pay the extra for the 16gb just in case. The question is can I still get a 16gb if I return the 8gb and pay 100.00 extra? Please let me know asap. At&t service has really gotten better in south Florida.