Havent read through everything, but I really dont like this idea of grading a book based on scans/pictures. Sure it will give a base grade based on how the book looks in the pictures, but anyone can simply learn how to grade better, gotta start somewhere right? There are thousands of graded examples of professionally graded CGC books to choose from with the respective number grades and use those as a rule of thumb to grade.
With scans/pictures, they can enhance the appearance of the images and even hide any important defects associated with the book. Not to mention other things unseen (missing pages, stains in the interior, rusty staple migration, etc.