I have a battery grip for the D800, but I have found that I really don't like it all that much.
My main complaint is that you have to remove the grip to replace the second battery. This is time consuming, and it is pretty hard to get it tightened back up where it needs to be after each change. On my D200, both batteries were replaceable without removing the grip, and I liked that.
As far as better support when shooting the D800 in vertical orientation, I have found that I rarely need to turn the D800 vertical. I have found that there is so much resolution that it is perfectly acceptable to shoot horizontal and crop a vertical out of any image. And you end up with more resolution than my D3!
Shooting everything horizontal has the added benefit of hiding the flash shadow when shooting receptions or events, so that you don't need to use a flash bracket.
My D3, of course, has the grip built in, and I really LIKE that grip. There is only one battery, and it can be changed in about two seconds. And it will last for at least 12 hours of continuous shooting!
I'm just curious how much you like the battery grip on your D800?
Count me as one of the people who just runs a battery in the grip and none in the camera. I do this on my D700 as well with an en-el4a and get roughly 3500 shots per charge shooting compressed loseless RAWs under most circumstances.
I would like to get an en-el18 for my d800e to go from my current en-el15 shot total per charge (about 600-700) to something closer to 1500, although I hear 1200 is more likely. Right now I have 3 en-el15's to make sure I am covered for longer shoots.
I guess they thought with the much slower frame rate we would just take less pictures per session!
Funny; that's exactly how my D300 grip has worked. I never found it to be a problem, or time consuming to unscrew the grip so that I could rotate a fresh battery into the body. Over 215,000 clicks (including recent shutter and mirror replacement) and it's had the grip on it since day one.
One thing mentioned by a few people is that you can run one battery in the grip and leave the body empty. It works fine with an empty grip as well. I like having a battery in the body, but on occasion, have removed a dead battery from the grip to save weight. Always have loved the vertical shutter release and the feel of the body with the grip.
I'm currently looking at a D800e. I find the grip to be a bit pricy and may get the new camera without it. It's a very interesting point you make about not really needing to shoot in portrait mode. Great food for thought!
While we are on grips, how secure is the D800 in a triod with grip and L-bracket? I have not gotten a grip yet for mine because the camera is on a triod most of the time and I've been a bit concerned about having more stuff and connections between the tripod and the camera.
I didn't know you could run the camera without a battery in the body! That's always been a bugbear of mine to have to take the grip off to charge the body battery. Cheers guys, now I'll just keep the charged battery in my pocket. Much easier.
I use the D800 with a 3rd party grip and L-bracket without any issues on a tripod. The whole combo is solid. Since I have not compared it with a real Nikon OEM grip, I cannot say if the Nikon Grip makes it more stable.
I know there is a lot of talk about the grip being pricey. When I got mine, the first thing I noticed is that it is much better than the D200, D300. and D700 grips. It is contoured to have more bearing surfaces and has a "cup" that keeps the grip from wobbling as much as the MB-D10s.
I'm sure it's not like having a Dx body, but for a Dxxx body it is a vast improvement...IMHO.
Scott Chapin Powder Springs, GA, USA Nikonians Team Member
I bought a third-party grip soon after buying my D800e last year but never put them together. I was reminded about this recently, so I put them together and duh! I forgot how much like the ergonomics of a body and grip (I also have a D3s). I'm currently running with one battery in the grip.
Jon Kandel A New York City Nikonian and Team Member Please visit my website and critique the images!
Scott, regarding a right angle bracket and 3rd party grip, I bought a Meinke grip for my D800 and am very satisfied with it. High quality, I can easily get it on tightly and it's much more stable than the cheaper grip I bought for my D700. I use an Acratech right angle bracket with it. Works just fine, great qaulity also and it's made in the USA.