Hello, I have not purchased the product at Amazon, but I am so happy with it that I want it like you recommend. Habs for 21 euros at the store incl. 2 batteries purchased. The batteries are charged quickly and keep a long time. I have it now already almost half a year and play quite intense and still could not detect any loss in performance. I have not measured it as long as I use the batteries each, but it seems to me more than with normal AA batteries.
One thing I must still hold: If you can connect it directly to the XBox always load only one pack (presumably the power via USB is not enough). Since I have now connected a Kinect and operate on AC power outlet goes by charging both batteries simultaneously without problems.
