I'm thinking the gauge of wire makes a BIG difference in tone (almost as big as the magnet). In terms of DC ratings and magnets, the HD and NB were almost identical, their biggest difference being the gauge of wire they're wound with (44 vs 43). Dunno what other pups Tim winds with 44 gauge, but he told me that the NB, CS, RY, and Crawlers were all wound with 43 gauge and that was what contributed to their more organic tone......