i have often thought this too, i hardly ever use the regional unless i am miles from anywhere, but it is the lowest forecast pressure and so as long as you remember that and keep thinking ahead its the safest option some of the time. (I have never seen a huge diference between a qnh and the regional)
I have always found (with regards to terrain clearance and on QNH) that a lot of people always forget to account for the height of the ground and always over-read the altimeter (eg pfl's) so it all goes fuzzy anyhow as they are reading the alt incorrectly.
or is that just rubbish?
good topic though......