The documentation from Canon is very vague about this feature. It does say that the XPS driver has the potential to reduce banding, even on 8-bit images. I haven't seen any detrimental impact from using the XPS driver, so I use it almost exclusively. I can't say that I have seen any noticeable improvement. But I can say that I have been completely satisfied with the prints. If it works and produces good results, why not use it?