I had some years back asked on the military forum why the RAFuse QFE and don't want to change, I did not get a conclusive answer but the jist of it seems to be that it keeps the cockpit workload down for the fast jet pilots when doing PAR recoverys in bad weather ( no ILS fitted to some fast jets).
I can see the reasoning as these guys sometimes have to fly in very bad weather and using fuel reserves that would make a civilian pilots eye water.
From a civilian point of veiw I agree with IO-540 that the QFE/QNH switch during single pilot I.F. is an accident going somewhere to happen.