Most of my film bodies had grips or motor winders and having it there is what I'm accustomed to. It provides room for my large-ish hands, and it does (to me, anyway) provide better balance with my heavy f/2.8 lenses.
On batteries, AA Alkalines do not last nearly as long as the Rechargeable Lithium. AA Lithiums are better on life than Alkalines, but still not quite as good as the Rechargeable Lithium. AA Lithiums are much lighter than AA Alkalines, but heavier than the Rechargeable Lithium.
The extra battery duration with one in the camera and one in the grip allows me to shoot all week in a National Park without needing to charge. I carry the AA holder (that comes with the grip) with AA Lithiums as an emergency source just in case.