As I said in my 1st post Gasax , I've never experienced electrical failure, so the risk of it's occurence is probably more perceived then real.
What is "KISS" by the way?
With regards to certification, the SMA people told me the manual control backup was a requirement of their JAR certification. I wouldn't have thought that such a system would add much to the complexity, weight, or cost of a diesel engine, but then I'm not an engineer.