Dear all, Thanks for the informative replies. I gave zotero a short-test yesterday,and in general liked what I found, although as it uses sql databases, it is moves away from my preference for plain text files to see everything in. I appreciate that sql may scale better, but I don't have huge databases. I think I'll continue to watch how the zotero standalone develops.
In the meantime, it made me think a bit more about looking after pdf collections. I'll try out using org mode for annotating my pdfs, to see how that works. I had not seen recoll before, that certainly looks nice. Will feedback to the list if I have anything useful to add. Stephen