It looks to be slightly longer than the Mophie and not have the vibrate switch cover either. It does however appear to sync through the micro USB which to me is a plus.
I like the Resurgence from the images. I've been using a Juice Pack Plus and Air for the past year. I alternate cases depending on power needs as the Plus is quite a bit heavier than the Air although not much bigger physically.
The big negative though is the release of the case this close to the inevitable iPhone 6 release. For a new battery case buyer it does add to the market but even though I would like a different case just to mix it up as the Mophie is kind of plain (both of mine are black) I just don't see the point of spending that much on a case this late in the lifecycle.
Hopefully with the Lightning port no longer in infancy the transition to the next iPhones, whatever they end up being, will be short.
