The pipe between the reg and rail on the 2wd can perish, like any pipe, and especially when 20+ years old, these can be replaced cheaply for well under £1 with some 8mm OPA, the original size was 7.92mm!!, but 8mm is fine.
I don't think the change to the 4wd type was anything to do with safety, but more likely aesthetics, and I would say the 4wd one is better, I know which one is easier to check the rail pressure on for the average diy'er, it may have been changed due to commonality of parts thing with other cars, if ford were on the ball they could easily have fitted a shrader valve so the pressure could have been check easy, but they didn't.
tabetha