I was one of the first to ask about RAM. At 512MB of RAM, iOS7 pretty much fills the entire cache with about 400MB of RAM usage for basic functions. That's a pretty heavy OS. For Safari users, that means probably about 2-3 websites not in need of refresh when tapped. At 1GB of RAM, it's much better on an iPhone 5S. If the iPad Air or iPad mini w/ Retina have 1GB or more of RAM, it means that it will run more smoothly. Another thing I have noticed is that if the app you're using can't access enough RAM, it will just open and crash/close. With 2GB of RAM, the devices will be future-proofed longer and will be able to support more documents/apps being open at once without paging RAM.