I agree that the PN 5, 6, 7 etc, have improved edge cleaning. In regards to cleaning ability, I feel that we're better off with a 12 inch wide unit than a 15 (both identically designed) in that air velocity at the head is increased with the 12, causing better dirt pickup. Lux builds a great PN, but if you want a nozzle that eats them for breakfast in my opinion, buy a 12 inch Lindhaus and use it on your lux. The cleaning ability is greatly improved, not that the lux is any slouch to start with.
Vernon