After all the discussion about the A7R II, I decided to try it for myself with the Metabones. I returned it after less than a day, not because it was a bad camera but it wasn't for me and my own purposes. It was small and light - it looked and felt to handle exactly like my 3G X, both having a suspiciously similar ev adjustment dial, a feature I like. The 3G does have the advantage of a touch screen and a built in lens! Big pluses of the Sony are that the IQ is very good indeed and you don't have to AFMA lenses. The camera worked well with my old 24-105mm for general photography and landscapes. There were several downsides. The first was the menu - it is as clumsy and ant-intuitive as rumoured, and I first had to trawl the internet to find out to format the SD card, as it wasn't in the guide and was eventually located in a sub-menu. The battery life was appalling, and it was quickly drained by the 100-400mm II.
The killer for me is that it is not suitable for my type of nature photography. The problem is that I need centre spot focus for bird photography with precision for picking out small birds between branches. So, in this mode the Sony does not use all the focal points in the sensor, which slows down focussing, and I didn't learn how to use just a tight spot focus, if one exists (it's like using the 70D rather than a 7DII). The focussing would be fine for a bird in flight or one without an obscuring background. The IS on the 100-400mm II worked fine when it was turned on. Unfortunately, turning it off didn't seem to activate the internal iS of the Sony, or if it did it was lousy for a telephoto. Perhaps I have missed something.
The other important factor is that as now is becoming common, I use the telephoto lens and camera as a hand held spotting scope (with excellent IS). The optical finder of the 7DII and its x1 magnification is better.
The Sony is clearly excellent in many ways, but it's not for everyone.