I have a canon g6010, it's the same thing as the G6020 but it's sold in Brazil and I really like its duplex function, however I wanted to print in duplex but in grayscale (B&W), but instead of using just black it uses colored ones to create shades of gray, so only using black when it is a stronger shade of black, unlike the simplex mode in which it uses only black, and in addition it loses a lot of speed, since the black print head is double the size of the color print head, but then it ends up using the size of the color head and using the color to make the shades of gray, thus losing a lot of speed, I wonder how this would work on GM series printers, since use the same structure but only have black print head
