I want to be able to increase the battery life of my iPhone 3GS, and I am debating between the Mophie Juice Pack Air and the Ivyskin Smartcase. According to their websites, both cases would have an equivalent effect on the life of my battery and the prices are the same, so I was wondering if anyone else had experience with either case, and could recommend one over the other. If the functionality of both is the same, then it seems like the mophie juice pack air might be the better choice because it looks a little better, but any opinions would be greatly appreciated. Thanks in advance.