Has anyone tried out any of those backup battery cases? The Incipio offGRID or the ExoLife S4 case just to name two that I've seen online. I just got the phone, so I want to look into all the options for battery life on the phone. An extended battery or a spare is the easy way to go, I know, but I was just wondering if any of these are even worth trying? Any input would be helpful. Thanks! 
