Well
It looks as if MF digital backs are extremely reliable. Full marks to the manufacturers.
John
No, certainly not, and there have been lots of comments here and in other forums through the years. Every single brand has trouble from time to time, yet there are always people who do not experience any problems, or find solutions to everything.
Personally, my back (Sinar eMotion 54 LV) had problems crashing for a long time, until I took everything apart and cleaned all the contacts, then it stabilized. It still crashes once in a while, but no more often than, say, a Windows PC, so I consider it normal at this point. There is also an issue with the occasional dramatic under-exposure, but again, I suspect contacts or my camera (Contax 645 AF), which is a bit older and probably needs maintenance.
There are also issues like how does the back respond to incorrect settings, like in my case, writing to the CF card when the main buffer is full (there must be room for one image, since it is stored there temporarily), and so on.
Phase backs have had issues with colour casts, CF Card recognition, and so on, but perhaps Phase owners can speak up here. Leaf I don't know exactly, Hasselblad I don't really remember either, but I am almost certain that I have read of problems with all the backs. None are as reliable as film, but I think they are all reliable enough, with the possible exception of some of the Mamiya backs, which could be pretty flaky.