So I was looking around and saw this battery case was announced. I know Mophie offers 60% more battery but for $10 more I could have 120% more. I'm looking at this from a value standpoint as it offers all of the same functionality that Mophie offers in a slim package with higher capacity battery.
http://www.phonesuit.com/iphone-6-plus-battery-case-phonesuit-elite-6-pro
http://www.phonesuit.com/iphone-6-plus-battery-case-phonesuit-elite-6-pro