I have be fortunate in that I have never experienced any car failures, staying loyal to Nikon I have mainly been using CF Cards in the D100, D200, D700, D800, D800e before changing to XQD in my current D850.
I can understand the concerns of photographers who are covering one off events weddings immediately come to mind when there is no second chance should the photographer get back to his computer and find a card problem has resulted in corrupted image files.
I ceased wedding photography before quality digital cameras became available at an affordable price, there was similar concerns having exposed 6 rolls of 120 film, they were sent off to the lab and the wait to see if I had made a competent job a week later, now I am purely a leisure photographer, both card slots have a card installed but I would be annoyed if for whatever reason the image files were corrupt
It is unlikely I’ll part with my D850, I tried and struggled with the electronic viewfinder, that is probably a ‘ me ‘ issue rather than a camera issue, I would have given the Z system greater consideration had there been a reduction in the lens size, I am sure the new lens are optically better due to more recent designs etc but at a quick glance the lens look like there has been a spacer added at the rear of the lens, resulting in a more compact body but out of proportion lens.