I may be missing the boat here, but I have been evaluating DT for my use and found it confusing to the extent that I am not using it to its best.
Here’s the problem.
I have a "mess" of documents relating to a specific project and they are in a specific folder in my Documents. They consist of MS Word, RTFs, PDFs, some JPEG scans, etc. Some of these documens are rather large PDFs of up to 100 pages. I tried a simple search to see how DT works and I was VERY impressed at the speed of the search. I got a ranked list of documents that contained the term. Now, of course, some of the files were easy to locate the term because it was highlighted. But in the large PDF file, all I got was the file in what looked like preview without any search function. I would have to go into Acrobat to do a search. Not so good. What am I missing?
What happens when I add documents to this folder? How do I update? I already have dupes in my DT library. Is there some one of automatically or at least semi-automatically updating new material into DT? I’m stumped.
It woulod be good if I could organize my e-mails with DT. At the moment all I can do is bring them in by printing each letter to PDF and saving it in the appropriate document folder. And then we have the search issue again.
I think this is a very promising technology and I would like to help it grow. Please let me know what I am either doing wrong or not doing.
 On the issue of searching PDF documents: I’ve got many PDF files running into the hundreds of pages in my database. Currently, DEVONthink can only display the first page of a PDF file found in a search. Like you, I don’t find this satisfactory. That’s why I import PDF files as text or rich text, rather than storing them in the database. That way, the original PDF file remains outside DEVONthink, but its text is stored in the database and is linked back to the original file. To do this, go to DEVONthink preferences, select the option not to import PDF files to the database, and also the option to convert PDF to text. (One of these days, when Apple supplies developers with more ‘hooks’ to Preview displays of PDF, I would expect DEVONthink to develop very powerful PDF search and display features.)
 Importing email into DEVONthink: AppleScript may solve your problem. Check the scripts folder that comes with recent versions of DEVONthink. You may find a script that can transfer slected emails from your email application – and the files will be imported as text into DEVONthink.
Unfortunately Apple’s Preview uses a private solution - there’s no way to search, highlight or copy text using Quartz (and Quartz displays the PDF documents inside DT). Hopefully Apple will release the frameworks to developers rather sooner than later.
In addition, version 1.9 will feature synchronization and therefore the folders of your harddisc and the DT database will contain the same data (well, almost…). But don’t expect v1.9 in Q1 - DT Pro has a higher priority finally.