I've had three engine shutdowns in the past 16 years I've been flying with my current job. One was catastrophic (as in fire, wetting of pants, etc..) and the other was a commanded shutdown due to a problem. The third..was a bit of a glitch in the Matrix.. So *my* rate of engine problems is about 1 every 3 or 4,000 hours. I don't know how you would approximate that in DCS World, but it couldn't be done with a 1 to 100 slider for sure...gotta make that slider 1 to 10,000 or something..
BeachAV8R