For those interested I just measured the readout speed for the A7R6 (as well as A7R5 and A1 II that I have at hand). I had preordered the camera and it came yesterday.
I used a pulse generator driving a high speed LED to generate a precisie optical waveform and capture it with each camera (will put more details on my channel)
summary
--------------------
A1 II : 3.9 msec
A7R5 : 94.35 msec
A7R6 : 19.7 msec for RAW (Lossless compressed or compressed HQ) / 14.1 msec for lossy compressed
it is quite a bit behind A1 series
one pleasant surprise : In A7R6 the EVF resolution does NOT drop like all other Sony cameras when you engage the continuous AF by half-pressing the shutter. It remains high and the EVF brightness is great as well
