Like you, I don't have the AE Prism Finder II as the older one works just fine. I can't source a manual for the new version but looking at the specs from Mamiya, it appears that the older type may have an advantage in Auto mode as shutter speeds are stepless whereas the new version only offers speeds in 1/6 EV increments. Its a minor point as, with 1/6 EV steps, no one is likely to spot the difference in exposure to be found between any 2 of those steps.
Originally Posted by brucemuir
So, other than perhaps having more robust electronics, it would seem there's little point in paying the much higher price for the latest type...unless someone can explain what I've missed?