jezzes chr. are you guys lotto winners, are you divorced or singles - man, stocking 400, 500, 600, and an incoming 800 + a D4 and D800 body, and I assume also stocking the holy trinity. I hope you are well insured.
What a fantastic setup to own, but I'm not sure I would even dare to leave home, I don't own half of what you have got and still I'm worried when I leave the house - insured or not, no one want to loose this kind of stock.
Anyway, I have a MD12 for my D800s, the built quality is better than the copy grips and it fits tighter and when fitted it doesn't feel as much like it's an add-on as the copies does. The thing is, I just don't use it any more, I tend to just carry one or two extra batteries in my pocket or bag, and usually I never need to replace the battery during a whole day of shooting, well of course, if I'm using my 500 with VR on for shooting trackdays it drains much faster, but I have basically stop VR anyway. I have switched off the auto preview, in fact I did that many years ago and that preserves quite some energy.
Congratulations on the purchase, remember to be patient and it will reward you big time.