I got a spare iPhone 5 laying around that has iOS 7.1 installed (not 7.1.2). I'm thinking about trying the iOS 9 Public Beta on it, but if I do that, I can't go back to iOS 7.1. My only option would be to go to iOS 8.4, which I know from my main iPhone 5 runs slower than iOS 7.1. With that in mind, do you think trying the beta is worth it? I'm interested in the new features.