OK so I just finished using the Gold 4200. It went 41 hours when it reached 15% when I shut it down and put in the stock, fully charged, at 11:17 pm est last night. I tend to use very little that drains or syncs such as "no wall paper" and very long sync settings. Much of time is spent on wifi and do no music or video, or rarely so. My suspicion, or hypothesis, is that there will be very little difference, if any between the "Gold" and the stock, but I do have an open mind. Still awaiting the delivery of the 6500 Onite which will arrive while I will be away. Sorry for the delay to all my fans. In the meantime have also been looking for battery charger for the bigger batteries. Not sure the ones I've seen will accommodate the higher contacts such as the nice stand/charger described above. Took a 2 1/3 buck chance on what is billed as a "Universal" charger in that it has movable arms to adjust for different contact points. Has gotten mixed reviews at Amazon but I thought I'd risk the $2.33 including shipping. As you can see I am a risk-taker.