> the battery life is barely a few hours and the sound quality is ok... Often only one headphone will turn on but not the other.

Sounds like they are broken. I have XM3s. The batteries last for a very long time, something like 12h with noise cancellation on. I've never had an issue with the speakers turning on or off individually.

> Always have trouble with voice quality on calls too.

Their mic is their biggest weakness. It's pretty bad.