Ok, I wrote a post earlier, but Apple deleted it due to mention of beta versions. But now the beta is public.
But as I have posted before, I had big problems with loss of connection. The actual case was that the Bluetooth on my iPhone 7 went off, disconnecting both AirPods and Apple Watch.
I tested the trick which involved resetting AirPods, disconnecting all Bluetooth devices and also turning off iCloud on the phone.(and then everything back again) I did all of these steps, and first attempt to make a call was without any improvement. Then, what I did was to make a call, wait for the Bluetooth to drop out, and then at the same moment I did a hard reset of the phone. If it was just luck or if it just needed the reboot, I don't know. But after I did these steps, the AirPods have been working flawlessly. And this was before I installed the iOS 10.3 Beta. And I can confirm that they still work after installing the iOS beta.
I'm using iPhone 7, with Watch 1 st. gen.
Beta OS on both iPhone and Watch.
I'm very satisfied with my AirPods.