I always carry a spare battery but have never needed to use it; although I always start the day with a freshly charged battery.
The grip adds weight and seems cumbersome to me.
I was actually discussing this very point with the photographer from my local paper recently. He told me that he uses the grip for that very purpose, to add a 'holding handle' when rotating the camera to shoot in portrait sizes.
So I rotated my camera, same model, to demonstrate that the grip would get in the way for me. Apparently I am rotating my camera the wrong way! Anticlockwise not clockwise. But going clockwise hurts my wrist when I try to click the shutter.
It just feels more natural for me the way that I do it.