I've been able to do this successfully with my app that's in the App Store. It supports armv6, armv7, and armv7s and iOS versions from 4.2 to 6.0. I've verified that it runs on older devices (iPhone 3G, iPod touch 2g) all the way through the iPhone 5. This method requires having both Xcode 4.5 and an older version of Xcode installed simultaneously. I'm still on 4.3.2 for my older version, but 4.4