Canon Pixma Pro-1: soft image output

I own both the Canon iPF6100 and iPF8300 printers. A while ago I bought the Pixma Pro-1 so I could effeciently print 8.5x11 and smaller more effeciently and with bleed and print multiple copies without having to reload paper. On a lark, I took the same layout for a folding promo that I had printed with the Pro-1 and printed on my iPF6100 with the 3mm margin setting, figuring I could always trim. While the color was essential the same (good profiles), I was astounded how different the sharpness was. And this was with the Pro-1 on its highest setting and the iPF6100 only on High (not Highest). The sharpening was identical because it's a layer on the image file (I often use Jeff Schewe's sharpening tool). Any thoughts on why this might be so different?

Nemo