I'd stay away from the Sony A7R. I played with one at a real brick and mortar store (BCooter is correct-Sony is a wild card). I also checked out the Fuji and Panasonic mirrorless cameras. I opted for the Olympus OMD EM1. I only shoot stills. If I shot motion as well as stills, a Lumix would be on the very top of the list.
I have a Nikon d800; the 14-24 lens is a miracle of science. But I love the Olympus more than any camera I've owned--that includes MFD, APS-C, FF, FX, 8 X10 film, 4 X5 film, 6 X6 film, 35mm film, 35mm half-frame, and Minox.
Pixel for pixel, the 16mp Oly cameras do a great job. I love the affordability of the fast primes. I've blown up some of the files to app. 24 X 32. Sure they are a bit noisy, however I rather like the look. I also have an EPL-5 with a VF4 EVF. I am taking more photos now, for the sheer joy of it, than I ever have.
The D800 is fine for my commercial work (although the red-channel often drives me crazy). Oddly, an Oly is sometimes the better option.
As far as MFD goes, there is no way you will be able to put together a system for $7K and be happy with it over the course of a year before you'll want to throw more money into it to broaden its capabilities. MFD does weird things to otherwise rational folks. Unless your living depends on fine art reproduction, ultra high-end tabletop, or noiseless giant-size prints, I'd nix the idea. If you have a trust fund, go for it. Or if you really want something expensive and neat, go for a Leica M9 and a couple Voightlander lenses.
I owned a Hassey CF39-MS, a compliment of lenses an HD body, and a pancake camera with an amazing 72mm Digitar equipped with an electronic shutter (prior to that an Ixpress 384C + Mamiya AFD). The files were gorgeous. The color out of the box was great. However, The dynamic range wasn't as broad as my Oly EM1. The HC 35mm lens is junk. The HC 28mm lens is quite good, but costs about as much as an Otus. I hear the new 24mm is excellent, but very expensive. I am sure you can find a Mamiya AFD II or a V Hassey, a P1 back, and a lens or two within your budget. But you will have a hard time finding an affordable wide angle solution. Whatever the case, your MFD solution will be technologically less sophisticated than currently available smaller format digital options. Funny, all of the MFD players are transitioning to CMOS sensors.