So I'm currently iOS 8.3, but I really want to utilize Apple Music and can't. Would you recommend an iOS firmware upgrade download for say iOS 8.4 or iOS 9.0 or should I just wait it out? I'm not terrible worried about some performance degradation (as long as it doesn't put me back to anywhere near iPhone 4s performance... that was way too slow!), but rather glitches and battery life as I'm out and about a bit and really need to rely on the battery due to not having access to a charger for multiple hours at a time. All of your input is greatly appreciated, thanks!