People only want to read an interesting and meaningful story. You will get more and more diggs, if you think about the real visitors not for the search engines.
Is it worth submitting a bunch of stuff to digg without investing any time... just to get back links, and since the keywords in the teaser that you submitted to digg will climb up the google chain faster, that could be an asset. Sorry to hijack, just would like a few thoughts. thx