I have been using the A7R with my Canon lenses and the metabones adapter, and I am very happy with the results. The 24-70 f/2.8 II is really nice lens on the Sony. The Autofocus is really sloooooow, BUT extremely accurate - no stinkin' micro-adjustments necessary, so I can't complain about that either.
The only thing that bothers me, is perhaps surprisingly, metering. I tried to use the live histogram (I think it would actually be a cool thing). But when I Expose to the Right (ETTR) on the histogram, I get a lot of blinkies on the final image. Even using the blinkies doesn't seem to be so reliable, as Lightroom shows the image with still some exposure headroom even when the sky blinks. I tried adjusting the Jpeg picture style - it helps get the blinkies closer to what I see in lightroom, but it's still not perfect.
So how do you do it ? Any tips and tricks ? Is there a way to use the histogram for accurate ETTR exposure ?