I appreciate the suggestion. This issue has since evolved, and the current state of the issue can be found at http://forum.support.xerox.com/t5/Copying-Faxing-Scanning/PDF-files-from-scan-are-much-larger-than-t...
Size of a file has little to do with the physical size of the document you scanned , it is in the details of what was scanned.
Copy either of the documents in greyscale then in color using all the same settings and you should see some more dramatic differences.
If you want to see a real change in a single scanned doc, when you enable color, also enable OCR on an all text doc.
I scanned two pages of 8.5"x11" in 72 dpi grayscale, yielding a 450KB PDF file.
I then scanned a 11"x17" page in 600 dpi colour, yielding a 528KB PDF file.
The total area of these two scans are the same, so I was expecting orders of magnitude different in file size due to the pixel density difference and the use of grayscale versus colour. Why is the KB savings so meager?
I am using a Xerox WorkCenter 7855.