I just called F&R Farrells to inquire about the Hering Charlie Musselwhite Chromatic (701). They said they aren't carrying it because "it's the same as the 501 but costs twice as much." I was under the impression that the 701 had a acrylic comb, and the 501 an ABS plastic comb. Did Hering change the 701? I know they've been having problems keeping up with demand...