I think the pdfs are going to trip you up. You may wish to investigate a tablet device (ipad, Galaxy, etc.) But that will negate some of your other points. I don't think you can have it all... at least, not yet.
http://blog.the-ebook-reader.com/201...r-pdf-viewing/
Other than being higher cost, you'll lose e-ink and lose long battery life. But you will gain all the open formats you desire and can get Kindle4pc, B&N4PC, etc. plus take care of your pdf file needs too.
Good luck.