High Wing Drifter:
I have personally never come across an example of using QNE for a letdown although I have heard of this practice somewhere in the back of my dim and distant memory. At Nairobi, Addis and Asmara for example, we always used QNH.
I seem to remember that trying to use QFE at Nairobi was the cause of the two BOAC aircraft (a Comet and a 747) which both managed to do a touch and go in the game park well short of the runway and, amazingly, survive the experience.
QFE would have come out to something like 837 mbs but the altimeter was set to 937 mbs - an error of some 3,000 ft!