I use the MAS version of the Authy BT app. It pairs correctly about 90% of the time. The remaining 10% it refuses to pair up, even with the iOS app open, but I'm pretty sure that's Apple's buggy BT drivers, not Authy. That 10% failure is a minor annoyance, but (90% of the time) the convenience of being able to easily paste codes into my browser already make the UX much better than Google Authenticator.
