It looks to me like ios7 and auto layout is partly about running on many screen sizes. Makes you think about future devices and how your code will fare. Worth thinking about.
We found the switch to first the iPad & then 4.0" iPhone screens to be greatly aided by IB. The fear (?) that's always keep us with IB is that eventually the device screen widths are going to increase -- tools are supposed to help with such issues, why not trust that IB will lead you there?
As a side note, I learned to enjoy Android layout systems. It was all a big mystery until I could finally test layouts interactively within the latest Android Studio [0] GUI. Although I'm not sure if I'd rather have a similar XML schema for iOS, I'd bet that the JetBrains folks might have already thought about doing this for their AppCode tool[1].
You might need to use IB.