Currently each student's assignment is stored in a separate directory under the the user's userid. This means that one cannot simply go directly into the moodledata file and retrieve all assignments in a simple manner. It is generally cumbersome to have to click and download each assignment before viewing them – particularly for large classes.
What I would like to suggest is a "Collect" button on the assignment page, which would iterate through all submitted assignments of a particular assignment instance, gather the most recent version of each and present the entire set to the teacher as a single ZIP file. This could then be downloaded, and all of the files opened at once for viewing, comparison or comments.