I don't want to hijack the thread, but a lot of D4 folks have mentioned questions with D800/D800E...and I wanted to add my opinion to the mix...
OK, my 2 cents...D800E is the choice and this is why...
I have had an MF back on a Hassie for a few years now, and I also own a Leica M9. Neither has an AA filter, and to me this issue is simple. It is all about the glass. If you have really great glass, you want nothing to prevent all the detail from being captured. Pro technique is of course required but assumed because few hobbyists could drop $50K on a camera or make big monthly lease payments. Someone who can legitimately make a case for owning this stuff has been getting paid for delivering the goods to art directors, etc., general expertise for a while.
Given NIkon's new 800s you can enter this rarefied environment for ~$3K, plus glass. There are new rules here, and folks all over will be experiencing them as the 800s become more prevalent.
Now understand there are no "affordable" MF or frankly Leica lenses, at least not new. The average prime costs the same as a Nikkor mega lens, like the 200mm f2, $5K+....and the quality is readily evident, no question asked.
So if you are using the serious pro Nikkor glass, AND again assuming proper technique for a hi-res camera trying to achieve top results, then buying anything with an AA filter like the D800 would be a mistake, IMO. Frankly, there are a lot of inexpensive Nikkors (and cheap 3rd party Nikon mount lenses) whose performance at best is comparatively lousy when you have a hi-res capture device, and this discussion would not matter.
Pro technique involves many things, like knowing the effects of diffusion in any given situation...but it is not always the aperture alone. Achieving maximum effective sharpness is different from simple numeric resolution...and this is the real goal of a hires capture device...to get you to that max possible with as many options as possible. A hi-res camera calls for clean technique to max it's capabilities. While you can get acceptably sharp shots with handholding, critical sharpness, generally defined as showing no motion artifacts or any kind at full size, is nearly impossible without a mounted camera, and all applicable dampening techniques. In my work, I get paid a lot more for shots that end up in print on a marquee or billboard. Generally, the art director would not consider exposures that are less than critically sharp for these uses. To that end, I use the 5 series Gitzo, RRS 55 ball, Sidekick, and usually at least 35 lbs. in weight bags, hung and on legs. I track the subject with hands on the camera, then at the moment of truth I release the camera and fire a burst using a cable release. There is no camera movement, although occasionally the first exposure may have some due to the frequency decay of the last vibration transmitted from my hands.
I have read in other forums here that some people think clean technique is baloney. I guarantee all the technology in the world have not defeated the laws of physics, or that only misguided fools spend thousands on camera support systems. I refer folks to an excellent article written by Charlie Kim of Markins: http://markins.com/charlie/report4e6.pdf All I can say is you need to know this stuff if you seek to maximize your camera investment, ESPECIALLY in a hi-res device.
One thing I have not taken into account is people using this camera for everything, or for something for which it is not best-suited for (like low light rapid action)...to me that would be akin to having just one hammer in the toolbox. Maybe that would call for the need for the 800....BUT IMO horses for courses, if you have a hi-res camera use it when its strengths are needed. OF course I forget that Nikon allows the user to "dumb down" the resolution on the 800s...I just cannot imagine why I would want to do that.
As far as the moire issue is concerned, honestly, I can count on one hand the number of times I have seen moire in a capture...it is not like it is a regular occurrence. I choose to shoot with the MF when I have a fairly static subject, and I am doing a billboard, banner, show panel, etc. or the art director demands it.
Truthfully, if the subject is dynamic I would rather have the Nikon in my hands. You would be amazed how many large format images printed on banners or walls are Nikon + Photoshop...with all the tricks available today, it is easy. 20+ years ago, had to do it all on 8x10'" if I had to go that big.
Personally, I will try the 800E, I have one coming, to get a feel for the image quality...but most likely I wait for a pro version. I hate the cramped body design, lack of integrated vertical grip, SD cards in general (I really HATE that Leica sticks me with this consumer crapola), moreover the inability to have 2 identical mirrored cards as I do in my D3s.
It will however, show just how good the Nikkors are when compared to other hi-res cameras. Should be fun.