After successfully exporting all stories and comments from the dot from its launch until the day before yesterday to xml (to have a basis for test-imports on other machines), I can give you a few interesting statistics:
Since the dot started, 2815 stories were submitted. 586 never made it to the front list (because they were spam, double posts or reposts). On those remaining stories, a total of 95562 comments have been posted, an average of about 43 comments per post. Pretty impressive numbers, huh?