After reading that others have had good luck with non-genuine PF-05 Canon print heads for the iPF 6400, I tried to save some money when my printer told me to replace the right print head. Not having a spare on hand, I purchased two "Druckkopf by Canon" PF-05 print heads from Amazon ($295 apiece), one for immediate use and the other so I'd have one on hand for the future. Each replacement head showed very faint irregularities in the lower left quadrant of the nozzle check that manifested itself as very faint banding on light grey portions of an image I was trying to print. I finally purchased a genuine print head from B&H Photo ($474) and problem is solved.
Fortunately I was able to return both defective print heads to Amazon for a full refund, but the process cost me two maintenance cartridges and I wasn't able to meet a print order by Christmas. Never again!