Hi, I have an iPad Mini 2 with retina that works really well for the trivial things I do on it. One of the things I like the most about it is it has an absolutely phenomenal battery life compared an Android I had in the past. I am still running iOS 7, as I read of many nightmares about 8, but iOS 9.0.1 seems to be pretty universally perceived as stable, and I'm thinking of finally upgrading. Again, I don't do much with it except web search, e-read and check mail, as I still prefer full-blown computers for actual productive work. Is there any reason to update? Any reason not to? Will it diminish battery life? Thanks in advance.