Has anyone figured out why the classic shaving filarmonicas (the 15/16s monsters) (which were supposed to the last in inventory) are such different animals from the old fashioned NOS filarmonica doble temples with the pastel scales?

When it's honed right (and that takes some dedication), the classic shaving fily is a nice instrument. But it's not in the same class as the beautiful old filies that take an edge immediately and shave so so well.

Were the last blanks just not ground by the same skilled filarmonica grinders? Did they fail to find a good retired razor maker (unlike whoever got all those old friodur blanks)?