Surely it's time to withdraw Regional Pressure Setting completely. It dates from decades ago when many aircraft flew non-radio and obtaining local QNH was difficult or impossible. Its use today merely increases the chances of regulated airspace busts (not to mention mis-setting and the consequences thereof).
The QFE setting is another potential source of airspace busts and mis-setting. For a typical VFR flight in benign weather (slack pressure gradient) with destination within 100 nm or so, one could set local QNH on departure and leave the altimeter setting knob untouched for the whole flight. If a MATZ controller specifies a crossing height based on QFE, acknowledge the clearance as given but fly on QNH plus field elevation, rounded up or down to the nearest 100 ft. Likewise for joining the destination pattern.