Bear in mind, too, that a pump failure results in an instant drop, whereas a leak is a steady continuous reduction.
Why is that then? Surely a leak gives no pressure drop until the pump inlet is uncovered and the pump starts pumping air? With a slow leak there would perhaps be a period of fluctuating oil pressure as the oil sloshes around and covers/uncovers the pump inlet. With a rapid leak such as loss of oil filter lid, I suspect pressure drop would be near-instant. And with a pump drive failure, surely it might not stop dead but start slipping etc, or if internal damage to pump gradually get worse. I just can't see how your statement is robust!
It does seem a strange (ie bad!) design that with 2 pumps you get 60 psi or so, with 1 pump you only get 1/10th of that. I'm still glad I fly EC!
HC