Thinking of going back to the iPhone just for the battery. I remember my iPhone 4 having an extraordinary battery life. Would last me 2 days with normal usage. How good is the battery on the newer iPhones? I'm interested in screen on time (how many hours can you get from your iPhone turned on from 100% to 0%). I'm also thinking of waiting till the iPhone 6 for the bigger screen and 2GB RAM (probably due to the 64 bit CPU). Thanks.