Thanks for your interest! I'm one of the co-founders of Taplytics.

Building for iOS in general has improved a lot. Apple has really cleaned up iOS and Xcode in the last two years, with ARC being a huge improvement for developers. Seeing that iOS 6+ is now 97.7% of devices (https://mixpanel.com/trends/#report/ios_7), we feel that focusing on iOS 6+ is a safe bet going forward.