According to the spec sheet, it holds 8000 mah, and the output is 5V and 2.1A for each USB port. So, it seems like a fit for beagle-xm which eats 5V and 750mA, and up to 3A with all the USB ports. It also last up to 500 charges which seems lousy by the way, but I'm just planning to use it on rare occasions and when I'm out of cellphone battery in the middle of desert.
Initial boot tests showed no problem, but I'm not plugging anything to the USB either; so I'll wait for a final verdict when using a USB based bluetooth, wifi or display.
Here are some pictures of how it looks:
 When ordering from buy.com and prompted to confirm billing address, I realized that I hadn't touched my account in 2 years since it had the address of the hotel I was at that time, I updated it and placed my order. Two days later, and like a desperate kid, reviewed the order progress and yes... the shipping address was the hotel; when contacting customer service, the guy said something like "Yep, I'll cancel the order and you can reorder again, just wait for one day for this to succeed", later on that day, I received an email: "Your order has been shipped" :/ .
Anyway, thankfully the hotel is in the same city I'm living now, so just registered my email for delivery tracking, went by and picked it up, no hassle, no sweat.