I haven't had a digital controller fail but I am sure they can and do fail. I am also sure they do not fail as frequently as the wafers do. Even the solid state part of the controller that works with the wafer can and does fail but it is rare compared to the wafer failures.
The main one on my cabinet is electronic, the backup is wafer. If I remember correctly, I always thought wafers were more accurate, but digital are more reliable, as far as failures. I think.