So you want to swap a Galaxy Note 2 for an iPhone 4s? I would say don't do it. Going from the Galaxy Note 2 screen to the one on the iPhone will likely drive you crazy in everyday usage. I switched from an iPhone 4 to an HTC One X and going back to an iPhone 3.5 inch screen seems impossible to me. Also, you say you aren't due an upgrade until September 2014? The iPhone 4s came out in October 2011 and the Note 2 came out in October 2012 so your going to an older phone, too. Also, if your getting it in September, Your getting a nearly 3 year old phone which you will likely have to keep for 2 years on a contract? I wouldn't even consider getting an iPhone 4s.
Sorry if I'm not understanding your situation properly. If that's the case, please feel free to completely ignore me 😛