As I updated last night to iOS 9.1 Beta 2, I realized that in 48 hours I'd be restoring a new iPhone 6S+ and this is my first go around on a Beta. Here is how I think we would need to proceed, considering that the new phones will be iOS 9 out of the box.
- Enroll the new phone into the iOS Beta program;
- Update new phone to iOS 9.1;
- Delete beta profile & reboot (for some reason that is what I needed to do last night to get it to show up);
- Software update to iOS 9.1 Beta 2
- Backup old phone.
- Restore from backup.