No I have never had a memory card fail; but my amusement was with the cataclysmic terms in which that possibility was presented, as-if that same single feature should be the overwhelming consideration for every other potential camera buyer.
I believe it is an important consideration for anyone shooting images that are not easily recreated at a different time.
As far as I am concerned, that is 90% of what I shoot.
In my 15 years experience with digital, memory cards have been by far the weakest link, not to say the only link likely to fail. The biggest problem being that most failures are not detected at the moment of shooting, but after the fact.
This doesn't change the fact that the a7rII is a very appealing camera, especially in combination with a Cambo Actus. But the single slot will be a major pain because it will force me to bring along a surface 3 to do images back up and check in the field which is incredbly impractical. So yes, I really think Sony blew it on that important aspect and my frustration is the result of my interest in the camera.
I haven't written anything about other buyers as far as I recall, please don't put those words in my mouth.
Cheers,
Bernard