I don't have the Pro-1000, but I do have the Pro-1 and I think it's fair to say that the Pro-1's extra shade of gray does help this printer produce very nice "out-fo-the-box" B&W prints, but it does so essentially acting like a very well profiled color printer with strong GCR (gray component replacement) for neutral and near neutral RGB values. Its grayscale mode is effectively a conversion of any RGB color image to the underlying color LUT in the printer driver/firmware. It's not like Epson's ABW mode which does invoke a different LUT for ink channel blending.
Bottom line, IMHO, is that Canon has provided a very nice B&W output for printmakers who don't want to tinker under the hood or up their game with third party RIPS like Roy Harrington's QTR rip, or go for the ultimate B&W experience which means putting a dedicated set of B&W inks into your printer. However, when I take the time to create a very careful custom built profile for my other 13 and 17 inch printers that have 3 rather than 4 level gray, the typical viewer would be hard pressed to tell the B&W output from any of them apart. On the other hand, die-hard B&W printmakers will get their noses right up close to the final print and check things like dot pattern smoothness, presence of color dots, tonality and especially shadow detail, and overall visual acutance of the printed image. If you strive to be in that elite group of B&W practitioners, then you will probably end up with a dedicated B&W printing solution like Piezography, MIS Eboni, custom diluted HP Vivera photo gray shades, and/or the QTR rip at the very least
cheers,
Mark
http://www.aardenburg-imaging.com