I've been using a NEX-7 for over a year and have some nice lenses for it. I've been very happy with the camera and the results it's given me. So I was skeptical about whether or not I needed a FF camera. But seeing the samples from other photographers, with the A7r, I decided to take the plunge.
I have four lenses that will cover the sensor, a Zuiko 28/2, the Sony-Zeiss 55/1.8, a Leica 90/2 Summicron-M (pre-asph) and a Contax Zeiss 135/2.8. The amount of detail across the frame, with any of the above lenses, is just stunning. The NEX-7, especially with the 24/1.8, focuses faster and is easy to handle—for street scenes it is superior, so I'm keeping it. (Sold my NEX-6 backup camera, though.) But I will be shooting with the A7r as my primary camera from now on.
The size and capabilities of the system just seems vastly superior to pretty much anything else. I have a small Thule backpack (that is within overhead compartment specs, 14x9x22), and I carry the following:
A7r with 55/1.8
NEX-7 with 24/1.8
3 additional lenses, the aforementioned 28/2, 90/2 and 135/2.8
5 Lee Seven5 filters, hood and adapter
A Giottos tripod (not a mini, it opens to 64 inches, and it's NOT strapped to the outside, it's inside the pack)
Extra batteries and cards, and more filters
I also shoot a good bit of video, and the A7r does that pretty well (1080p at 24 or 60fps). It also has manual audio level controls, a big improvement over the NEX-7.
Anyway, you can see some early shots from the A7r and compare to my work with the NEX-7 here:
http://behyer.tumblr.com