I have cancelled my pre-order for now. It seems the AF on these is not up to the D850 and D500 in terms of speed or AF tracking. Since I am beginning to do blackwater photography, AF and CAF tracking is an absolute key aspect of the camera and not something I want to compromise on. I am still reluctant to go to the huge housings for the D850 and D500. So, I will be waiting to see new developments later this year from Sony.
Sensor-based AF can't compare to a dedicated AF module (requiring a mirror). It's certainly come a long way but still a far cry for the foreseeable future. I guarantee you Sony won't suddenly revolutionize sensor AF later this year.