Moire is not something that you see a lot. But when you do get it, it is sometimes really hard to get rid of sometimes. Sometime you can ruin your picture in the case that the moire has taken a good part of your picture. They give you software but wait and see how hard it is really too get it out of your pictures. I need to find the link of a web page that was trying to remove it in Photoshop so you can see what they did with a bad case of moire and what the out come was. The time she spent on trying to fix it and what she got, she would have been better to just re-shoot the picture.
If your even at tad worried about the problem with moire, I would just get the D800 and forget it. If you are a professional that has to have every last piece of detail out of your pictures and make six feet pictures and don't mind throwing away a picture maybe now and then, get the D 800E.
I don't really think there is going to be that much difference between the two cameras that most people would even know looking at pictures from one to the other. Your going to have so much detail out of ether camera, how much do you need. And I am sure there will always be some people that will want more.
Moire is easier to get out in dark colors than light ones. You need to look when taking pictures like a shiny man suit with a repeating pattern in it to make sure that it didn't get moire in it. If it does change the angle or move forward or backwards to get an angle that won't show any moire in your picture. You can get a filter for you lens, if you see it when your taking a picture. Most of the time you won't even know you have it until you put the picture on your computer. I will try to find that Photoshop link and post it here if I find it.