I have a feeling the battery capacity may NOT be the only things that might have people rethink which model to get.
If rumors are true -
38% larger battery capacity
Less pixel density to push on a 0.8 bigger display (w/ same res)
Sapphire crystal screen
Faster clocked SoC
Better cam with OIS
128 GB option
I'm also wondering if the 5.5 gets out of the 1GB RAM limit and Apple gives owners at least 2GB RAM to show off the new iOS8 multi-app windows capability. Sony is guilty of the same thing with their PlayStation line. Every time they want to miniaturize or slim down, they also take away features to lower production cost. Ironically, it is their Sony Xperia Z1 Compact where they miniaturized the bigger brother without losing to many compromises worth losing like 2300 mAh for a 720p display.
Apple got away using 1500 mAh capacity for so long because not only because iOS is more energy efficient with background suspending, but because iPhones only had to power 4-inch screens with an oddball resolution that wasn't HD yet. I saw the Huawei Ascend P6 at 6.18 mm thick, but even its 2000 mAh just isn't enough for a 720p display. I'm hoping manufacturers start trimming the top and bottom bezels. Apple is guilty of having too much on the top and bottom. The often overlooked and forgotten Sony Xperia ZL proved you can have a 5-inch screen in a height similar to the Moto G.
By paying for more for a 5.5 model with a minimum $299 subsidized price, Apple will give you more.