All other factors being equal, it ranges from no difference at all between manual and power reverse to the power reverse being far superior in all respects to the manual, to to mention being safer to operate.
As far as fineness of settings, the old Precision power reverse (the screw type) had them all beat, as the engineer could make extremely minute changes. However, that screw also made it a bear to switch with, as it had to be cranked from forward to reverse.