My iPhone 5s is on 8.4.1. For some reasons 8.4.1 has a lot of battery drain bugs and I don't know if iOS 9.2 battery is good or not if I want to upgrade, Apple stopped signing iOS 8, so I won't be able to get back, I can sacrifice performance for the sake of longer battery. Does any one see iOS 9.2 good or better and can last for good amount of time?