A portion of a NE interview with VD-Dev...
: We’ve heard that IronFall Invasion will take advantage of the New 3DS’ C stick. Will any features that are exclusive to the new system be offered?
: the game runs on New Nintendo 3DS, it has special settings in order to take advantage of the new C Stick and the new shoulder buttons. For example, when you play on an older 3DS model with the Circle Pad Pro, shooting will be assigned to the ZR button. But on the New 3DS, shooting will be automatically assigned to R as the button is more comfortable to use on this model. Also, loading on New 3DS will be faster thanks to the hardware.
Full interview here