i have my upgrades structured to have one available for each new model, not the "S"s. for example, bought the 4 and upgrade was available for 5. bought the 5 and now heres my upgrade for the 6. IMO, the S usually has very marginal changes that don't constitute an early contract termination. from the 5 to the 5S, new color and a bit faster, ehh. the game changes now with the new screen size but honestly, the 5S is a great phone that i personally wouldn't need to upgrade to the 6 for