Is it safe to upgrade to iOS 7 on iPhone 5?

Asking again as I got no answers in phones section; I used to have an iPhone 5 which I updated to iOS 7 & then iOS 7.1.1 which I did straight away as soon as I got the phone. The phone turned out to be second hand used and was replaced by Apple Store under UK consumer law, there was a fault with the phone that I found out it was used, when the home button stopped working, but at the same time I had severe battery drain issues, where the battery would be completely drained in 20 minutes and even the aid of a Mophie battery case the battery was dead in 3 hours so I even got a DNS power pack too.

I now have a new iPhone 5 on iOS 6, the battery performance is not great either, to test it, I used the screen at full brightness & never turn off, location services turned on and currently have 4 hours. 46 minutes of usage with 7 hours of standby.

So I do not want to ruin another iPhone, is iOS 7.1.1 safe to upgrade to? Or is it best to wait for iOS 8? And do current iOS 8 users on beta program have any issues with battery performance yet?

I really liked iOS 7 and iOS 8 looks really good from the demonstrations I have seen, but really do not want a poorly performing battery

I had no issues with iOS 7 as far as battery life, and i'm currently running iOS 8 Beta and there's no battery draining issues at all. I think they are getting better with this issue so i wouldnt expect it to be a problem next year with ios 9 beta. You can install ios 8 if you want by getting a UDID activation

You can actually install iOS 8 now if you register your device's UDID with a developer account through a site like http://www.udid.in/ for $5. That's how I got it on my iPhone.

I've had my iPhone 5 for almost two years. It came with IOS6, and I changed it to IOS7 and 7.1. IF I have gps tracking devices switched on, my battery runs out mid-day. By switching off the gps options (or most of them), it runs fine all day on a single charge.