From my new 5x7 pinhole, loaded with Efke positive paper:

Everything people have said about how touchy this stuff is to work with... is true. A lot of my shots are nearly black+white (no grays), even with pre-flashing. Reciprocity failure is extreme, areas in light shadow on an overcast day could not be coaxed into showing any more detail from a two-hour exposure than a ten-minute exposure (which is to say, none at all visible to the eye, though you can reveal some with delicate scanning or backlighting).