I’ve had the experience of not updating from an iOS beta to the production release before the beta expired. Let me put it this way, an expired beta is not your friend.
If you have a beta release of iOS installed, you cannot upgrade to the production release over-the-air (OTA) through the Settings menu.
Here’s how to install iOS 8 on top of a beta release:
- Download iOS 8 (.ipsw) from iOS Dev Center
- In iTunes, do a manual backup (recommended)
- Option-click “Check for Update”
- Locate the .ipsw file
- Sip beverage of your choice while iOS 8 is installed