The 'garbled microphone input' seems a bit of a red herring, it's likely that the thermal throttling is kicking in which is causing the audio recording app to get slowed to below real time making it sound like garbled.
I've had the laptop for about a month now, and yes, Hangouts will bring it to its knees, but for some reason Hangouts will bring just about any laptop to its knees.
Battery life is as advertised, you do get 8-10 hours of web browsing, and shockingly, about 6-7 hours doing some light development work with Xcode. I've definitely had times when battery life seemed a lot worse than it should have been but that has been solved with a quick trip to Activity Monitor to see what's eating the CPU.
Spotlight Web Content was a common culprit so I turned off Spotlight Suggestions (also Bookmarks and History) and that made a noticeable difference.
I've only had heat come up as an issue once; turns out it needs to be on a hard surface when you're doing something CPU intensive. Who'd have guessed?