DC10RealMan, it is somewhat tongue in cheek but I think the RPS is a hangover from the days of non radio aircraft which needed a "safe" altimeter setting to fly on, hence the fact it is available up to three hours ahead.
With the type of airspace and traffic densities we are now dealing with and the fact that most aircraft now have radio I think it is far more appropriate to fly on the QNH of a nearby aerodrome rather than an area QNH. By all means retain the RPS purely for reference for those days when you are flying over the foothills of Wales of the Trossacks in order to check terrain clearance.
I am aware that the UK military system is oriented to RPS for calculation of Transition Level and minimum levels for aerobatics and spinning etc but they also seem to insist on QFE too - whilst we are about it let's get rid of the QFE.
They seem to do quite well in the USA with just one "ALTIMETER" setting (ie aerodrome QNH) - they don't even call it by a Q code - when was the last time we used these? I would suggest that one altimeter setting used by all airspace users would be far safer and easier.
No doubt the supporters of QFE (and RPS) will come up with all sorts of reasons why that system is better!