Resourcemagonline posted the content of an interesting chat with Sony US manager Mark Weir:

1) Why the A7rII has tilt and not a flip out screen:

they made a conscious choice to make their rear LCD a tilt screen rather than a full flip-out screen. They believed that the compactness of the camera trumped the space it would take to add a hinge and provide a full flip-out screen.

2) Why the A7rII doesn’t record 10bit video:

The inability to shoot 10-bit is because of the processor. The BIONZ X processor in the Alpha series cameras can’t actually process anything past 8-bit 422.

3) Why the A7rII cannot do RX100m4 alike frame rates at 1080p:

The sensor Sony is using in the cameras that have HFR, the RX’s EXMOR RS sensor, is a stacked CMOS sensor. Such a sensor uses a different means by which the info is taken off the photo sensitive layer of the imager: the destination is behind the imager instead of going around it. The upside is that it is a transfer that is drastically faster than other means, and it opens a drastically larger pipe for information. Transfer rates are up to 5x better than before.

The EXMOR R sensor found in the a7r Mark II does not enjoy that structure, so cropping in on the sensor would not realize the transfer rate necessary nor does the a7R II have the D-RAM required for it to process that amount of data. So the problem is two fold: the data can’t flow off the sensor fast enough, and there is no place to put that data even if it could.

4) Difference between Exmor RS (Stacked) and Exmor R sensors:

The capabilities of the EXMOR RS sensor are meant to be fast readout, and that’s where it excels. The EXMOR R sensor excels at balance between sensitivity and high resolution.

5) So why can the GH4 handle slow motion, internal 4K and 10-bit 422 recording with an external recorder?

Well, the GH4 is bigger (if you can believe it, yes it totally is bigger than the Alpha series cameras) and therefore their issues with thermal management (which, if you read around you’ll find is a common complaint even with the newer, beefier bodies found in the a7 and a7R II) are not nearly as extreme. Also, Sony has added that internal sensor stabilizer, meaning they’ve got even less room to use in that tiny body than you might think. And then of course you look at Panasonic’s processor, which however it works, manages to do the things the Sony one cannot, given the size of the sensor and the heat situation with the body.