It is a lifiting experience to once in a while use a Leica without any finders at all, like the Standard Leica. It makes you enjoy photography in an oldfashioned way. I try to use the Elmar 5cm/3.5 with the finderless Leica so that I get the old look. Surprisingly, I got fewer chopped off heads with the Standard and no finder than with a Zorki-4 which has a finder. Using the old Leica made me concentrate fully on zone focusing.
All this talk about finder lines is not too exiting for me.