Originally posted by wmsnyder65 Having two batteries in the grip as other manufacturers do is one of the main advantages of having it in my opinion. The only other reason I can see for using this grip is if you had very large hands as this would help with handling.
But don't those grips take up the body's full internal battery compartment? So you still only end up with two batteries.
Also, if you ever tilted the camera for portrait mode and do the stupid chicken-wing thing with your arms, you'll know how much more stable a vertical grip allows you to be.