Wow! Lots of minutiae in compass types and variations, but it looks like all, or most, at any rate will steer you to your objective and back again, if used in anything like a proper manner.

There is another major variety we have not mentioned yet, the Suunto B-14/20 (the difference being either a plastic or aluminum housing). This instrument contains a rotating compass card and a viewing window. Observing and the compass card with both eyes open, the images are superimposed and a very accurate bearing is obtained - easily within 1/2 degree. I have worked with these primarily in cave surveying, along with a clinometer working on the same principle, and have seen surprisingly accurate results achieved.

Back when I was courting Mrs. Hikermor, I bought the aluminum version and had "To Susan with Love" engraved on the side. I am sure that compass is the reason our marriage has remained on course for a quarter century....Just another use for a good instrument.