This is Canon marketing speak but here is what they write in regards to why their printer is better (I don't buy much of this except possibly the speed differences.)
Taken from here:http://www.digitalgraphicsresources.com/Pr...ive%20Guide.pdf
Let’s now take a look at the key competitors in the large-format printing marketplace.
EPSON STYLUS PRO 11880 64” WIDE-FORMAT PRINTER
Pros: This new professional-grade printer announced by Epson in Q2, 2007 is a large 64”-wide printer priced at $14,995. Featuring Epson’s new MicroPiezo TFP print-head with nine ink channels and a total of 3,240 nozzles (360 per ink channel)
this new model is faster than earlier Epson products and offers high-resolution output up to 2880 x 1440 dpi with variablesize ink droplets as small as 3.5pl. Though the printer has nine ink channels, it prints with only eight at a time. Like earlier Epson printers, the 11880 uses the UltraChrome K3 ink system with photo black, matte black, light black, and light-light black inks. However, unlike earlier models, switching between photo black and matte black is now automatic. This printer also uses a new ink formulation that replaces magenta and light magenta with a new vivid magenta and vivid light magenta. Epson claims that the new “vivid” inks enable a wider color gamut, particularly for blues and purples. Epson UltraChrome K3 inks are rated lightfast, up to 200 years for color images and longer for black-and-white images. A new 16-bit printer driver provides support for a 16-bit workflow on an Apple® Macintosh® OS X operating system. Flexible media feed options that support roll feed, cut sheet, and printing on posterboard up to 1.5mm thick give operators multiple options when it comes to media throughput.
Cons: Though the Epson Stylus Pro 11880 printer boasts a variety of impressive features, it falls short when compared to the Canon imagePROGRAF iPF9100 printer. Slow print speeds, a narrower range of colors, and lack of workflow and
productivity solutions will limit this Epson printer’s appeal to customers who need to produce ultra-high-quality photography and fine art applications.
Customers who need to work efficiently may be frustrated by the Stylus Pro 11880 printer’s slow throughput speeds. In Fine Mode (720 dpi), it prints at approximately 51 ft.2/hr.; in SuperPhoto Mode, it slows down to around 24 ft.2/hr.,
making it approximately 60% to 70% slower than the iPF9100 printer! Epson’s “vivid” inks might expand the color gamut in the blue and purple range, but what about the rest of the color spectrum? With the inclusion of red, green, and blue inks, Canon has expanded the printer’s color gamut to a range
closer to that of the Adobe RGB space. Canon’s wide tonal range, therefore, enables more faithful color reproduction of images captured by sophisticated digital cameras such as the Canon EOS Digital SLR.
Because quality output is heavily dependent on quality input, Canon has included additional software solutions such as Digital Photo Front-Access and the Print Plug-ins for Adobe Photoshop and Digital Photo Professional. With these additional
tools, photographers have more control over their images at every stage of the process. Producing accurate reprints may also be more difficult with the Stylus Pro 11880. Without a hard drive, print jobs cannot be stored at the printer and must be resent prior to printing. Without the ability to recalibrate the printer, customers may
also have additional problems matching reprints and colors from one printer to another. Though Epson assures customers that the printers are factory-calibrated, there’s no built-in mechanism to compensate for shifts that may occur due to
environmental conditions such as high humidity. Here’s the bottom line—for customers with high performance and quality expectations, the imagePROGRAF iPF9100 printer provides a wide color gamut and more control over image input and output with greater efficiency and productivity than the Epson Stylus Pro 11880 printer."