Daniel,
It will be a lot easier when you can search Hathi through Summon starting this summer. The majority of the content is in the public domain and that material is currently searchable through Google Book*.

One great thing that indexed Hathi content will offer Duke users is a click-through to Document Delivery so that when you run across those gems that Duke doesn’t have, you can easily request it. If you search Hathi here http://www.hathitrust.org/ you are offered a “find in a library” link which is really this key to accessing those copyrighted items that aren’t in the public domain, but Hathi gets that info from WorldCat, so I question why one would not search WorldCat from the start.

Your comment is really appreciated and gives us a lot to think about. Thanks!

*http://booksearch.blogspot.com/2009/08/download-over-million-public-domain.html