Now I'm wondering: A +/- 167feet accuracy (about 51 meters) isn't even as good as GPS is. And around my house, 167feet is surely more than the space between two parallel streets.

As I interpret the specs ("This precision allows you to place features that are next to each other on the ground in the correct position, relative to each other, on the map without overlap.)" it is saying that the placement of the streets and other map objects will be accurate relative to each other; but that you couldn't use any single point as an absolute position. Thus the map itself would be correct, but the corner of Third Avenue and Elm Street might not actually be at the exact lattitude/longitude specified.

This shouldn't offer any hindrance to navigation.

tanstaafl.