Erik, I have both the a7 and the a7R. I'm still trying to figure out where they fit in my collection of photographic capture devices.
I bought the a7R with the idea of using it for a specific macro-ish series in the field. The shutter shock put an end to that idea, at least with available light. Using trailing-curtain synch, I could make it work with strobes if I am willing to carry all that lighting gear around (it's not so much the lights, but the light stands and the diffusers and the reflectors and the softboxes...) So I'm either going to use the D800E for that, or stitch with the a7. The electronic first curtain on the a7 is a real revelation to this Nikon shooter, although I guess Canon people have had it for a while. A long shot is dragging a H2D-39 out of storage, but it currently is on the fritz. I'm not sure repairing it is worthwhile considering its depreciated value and its about-to-be-obsolete Firewire interface. If you're interested, I could go on for days about the Imacon SCSI to Firewire conversion and what a disaster that was.
The weight of the alpha 7s is not important to me, but the tilting LCD panel is a godsend. I can get low angles that my aging back made me give up on years ago. I can use less tripod extension and get more stability. Another great thing about the cameras is the crisp EVF focusing; it makes me want to slap my D800E every time I use live view on it.
I think the a7 is a better walking-around camera than its sibling. The AF is definitely better. But if weight's not important, the D4 is impossible to beat, IMHO. It's the first camera I reach for when someone says go somewhere and document an event. Fast, big buffer, fast AF, low noise, what's not to like?
For travel, I don't take the D4 unless I need to. The RX-1, and now the a7, seem to make excellent travel cameras. I'd put them clearly above the M240 in that regard if it weren't for the small number of Zony FE lenses and the user interface. The Zony lenses -- I only have the 55 now -- are light and, in the case of the 55, are, as you say, excellent. I consider my copy of the Zony 55 to be as good as a 50mm ASPH 'lux.
I wish Sony would employ the Canon/Nikon push-a-button-and-twirl one or two wheels UI. It seems like they're halfway there. The OK button in the middle of the four-way wheel is awful. Either you push it by accident or you push some part of the wheel while you're trying to push it. Nikon had this problem early on, and they still have the arrangement, but they made the switch detents stiffer, and they have an OK button well away from the wheel that you can use instead (unless you're changing the file name).
But I'm rambling. One group of people who might be candidates for the a7R are Canon users who've been waiting a long time for a dim light, high res body, but there's that shutter vibration thing.
Is is nice to have choices while we wait for the D4x and the $10K CMOS MF back. I've got a few Hassy lenses that I'd love to use on something modern, but MF prices scare me off, and at high res, you really need live view.
Jim
