Hmmm, seems to me that if a 'built in' offset was on some aircraft with new(er) kit, and not others, one would have the requirement for RNP 0.3 thrown out the window with the bathwater, and the whole idea would be a total and complete waste of time.
First it was....we aren't accurate enough (Navigators), then it was...we need something better that basic INS, and now it's...we are too accurate, so offsets are needed and should be mandatory.
Poppycock, I say...stick with the plot and fly the aeroplane on the airway centerline, instead of adhoc nonsense.