Ok so the more I'm thinking about it the more I'm tempted to spend the extra hundred and get the 128gb model...why the hell not. I already have the 64gb iPhone 6, have had it for a week today. Is it too late to exchange it? I bought it at Apple store if it matters. What do I need to bring with me? Will my upgrade availability be available as soon as I return the 64gb phone, or will it take awhile? Thanks for any comments.