I have an iPhone 4S, but have been thinking of switching from a small screen to a much bigger screen. I want to try the HTC One and S4 extensively, not just what I see in the store or what I read in clearly biased reviews. My contract ended two so I'm good for upgrade pricing. So I'm thinking about getting the HTC One, using it for 30 days, returning it, then buying the S4, using it for 30 days and either keep it if I like it, or return it and go back to the iPhone 4S and see what iPhone 5S will have in store. How does AT&T's return policies work? How does the contract work if I end up going back to my iPhone 4S?