I'm currently with AT&T and I'm considering the iPhone 8, 256 GB. What are the pros vs. cons to using the iPhone upgrade program other than the obvious that you get to upgrade after 12 months? I'm not sure that I would upgrade after a year and I can afford to pay full price for the phone. The only big thing that concerns me is that I might change carriers (to Verizon) over the next year. Will Apple swap the phone out at no charge if I decide to change from AT&T to Verizon?