If learning command and FJ bases want to fly QFE to make the circuit easier that's up to them. Personaly, I think Brize and Lyneham should use QNH. A moden FMS's VNAV function is designed to work on QNH, everywhere else in the world uses QNH so why have your home base the only place where you do it differently.
The danger lies where Civ / Mil traffic is using different pressure settings in the same airspace (as can happen at Brize when a charter requests or is given a QNH approach.)
Or when you're a bit knackered and can't remember whether or not today's approach minma is the one in bold writing.
Plus, Sector saftey is an Altitude. I've heared it briefed hundreds of times but never seen anyone actualy apply a correction for airfield elevation when they declare that they're through S.ALT. climbing out with QFE set.
Do what the rest of the world does, they generaly have more experience!!