I just got my 4S replaced via Applecare+. My old phone only had about 4gb of space available. After backing it up and restoring to my new (refurb) phone, I now have over 7gb of free space. I didn't delete anything, so did the process of backing up and restoring consolidate files and data so that I gained a bunch of space? I normally wouldn't worry about this stuff, but I'm thinking of getting a 5S and this would definitely effect my decision about how much capacity to get on my new phone.