Following much discussion on here (and, believe it or not, info from the super, awesome, hyperbolic Steve Huff) I have purchased the A7 rather than the A7r. I became concerned about the vibration issue, and in the end felt that the pixel differential versus ease of use clearly indicated that for a handholder like me, this camera was the way to go.
The camera is much easier to use compared to my Leica M240 (just take exposure compensation as an example) and the image quality is very similar. I used a 50 Lux ASPH at f8 to take my comparison images.
At 20 x 16 I am completely unable to tell the prints apart (Leica M v A7) at normal viewing distances. Even when magnified I have difficulty - though the M240 shadow detail is just slightly improved; maybe.
I haven't printed any larger prints as I don't have access to a bigger printer - yet.
I paid £5100 for my M240 and £1300 for the A7. I feel like a chump.
Leica - are you listening?