We concluded this experiment was a success.
It's nice to have a recurring calendar invite to open, click "Join Hangout" and start talking.
Gotcha: laptop/monitor switch
Google Hangout is sometimes choppy over wifi. The settings need to change when we switch from laptop to monitor, so we often are without sound for a few seconds before changing the "FaceTime Camera (Built-In)" setting to "FaceTime HD Camera (Display)".
Gotcha: choppy wifi
We've noticed in longer meetings, we sometimes need to refresh the page if sound starts to get choppy, presumably to clear some buffering.
Gotcha: internal microphone on a MacBook Air.
We've noticed during Hangouts that the sound captured by a MacBook Air's internal microphones is often muffled. We generally have MacBook Pros for better performance of test suites, but there are a few of us who have Airs. We use Apple earbuds with Hangouts on MacBook Airs.
For weekly retrospectives, one person is typically taking notes. When they type, their microphone will be muted. So, when multiple people are in the same room on a Hangout, we mute and cut the sound on the stenographer's laptop, restricting it to video and using other's nearby laptops for sound.
Overall, it's always better to see someone's face.