I've been shooting with the D800E for several months, now about 18k shots into it. My time has been split about 50/50 with portraits/cosplay and landscape photography.
No regrets whatsoever getting the D800E, I'm really excited to step up my work and take advantage of the new tech.
1. If you're not strict with how you shoot and what settings you use, the E would be a big waste of money. Without sharp lenses, the E would be a big waste of money. If you are sloppy, it absolutely shows in the photos (this also applies to the D800).
2. If you are strict in your shooting and have good lenses, the detail is incredible. Craftmanship of costumes can be showcased very well, since textures are captured so well.
3. The dynamic range is insane. When I would usually need a 3 stop GND filter now can be taken without one. It's a big deal. Especially when using high speed sync.
4. Moire is rarely an issue, even with all the different types of fabrics I end up shooting. Nearly all of the moire I've run into is while shooting cityscapes (railings in the distance and the like). It's pretty rare even then too.
5. Controls are slick. Very few issues. It's pro-style, which I prefer greatly.
6. Files are massive. Be prepared to optimize your workflow significantly. You will need a fast processor and a ton of storage space if you shoot a lot. For casual shooters, 36MP RAW on an average computer is probably a lot more hassle than it's worth.
I've shot with the D600 a bit, it's a pretty solid camera.
I think the controls would drive me insane.
It's much more reasonable for most photographers out there.