Sumnotes is the only simple, yet robust solution to scrape PDF books, lecture notes or research papers, helping you to focus on what matters to you. […] No installation, no adding bloat to your computer, everything you need is the internet connection and a web browser. […] Extracted annotations can be easily exported in to the DOC and TXT formats [and to Evernote!].
The point of this is to enable those of us who work on multiple PC’s to avoid lots of extra syncing and keep our file links intact. Mendeley does a great job of syncing references and maintaining links – IFF you let it host the files. If you do not, then it just syncs references and you have to manually relink at each new computer.