Hey... thanks for all the advice. I'm pretty confident of my decision to return it.
As for PDFs, I realize an iPad is better - I've got one. I also have the "original" Windows tablet with the Wacom enabled pen. At the end, after working with many alternatives, I basically print out PDF articles on scrap paper, mark them up, and then scan them in. I find when I'm doing research or teaching I don't read "one page at a time" - I'm not sure anybody does. When I'm reviewing papers or a thesis, I read one page, flip back to another page to check what the writer said originally, mark up the sides, etc. This is far easier on paper than a tablet. However, sometimes I just want to read a journal article and I was thinking that an ereader could serve.
What I did try was to convert a PDF to Word, and then I sent the Word document to the Kindle convert service: that wasn't too bad.
Looking forward to September 6!