All the literature says that charging the internal batteries takes more juice than just powering the device, so in my early test, I would say that 7 hours total battery time is easy. 8 hours is more likely and 9 is possible depending on the usage scenario and if your Q1 is topped off when you start. That's enough for me in most cases.
The Powerbank doesn't heat up at all. It never gets above room temperature so I'm only left with one suggestions for Samsung, make the cord from the Q1 to the battery retractable! I'll have a lot of out of the house time tomorrow with it. We're going to watch the space shuttle launch. It's a lot of waiting, a big wooosh, and long traffic jam to get home.