how to stop multiple versionf of Endnote from indexing the PDFs on each startup

I have my Endnote library on Dropbox, so that my lab’s various Apple laptops/desktop can all access the same library data when I run Endnote no matter where I am. It works great, and I was using Endnote X4 everywhere. Except, now I have a new laptop which came with OS 10.9, which won’t run Endnote X4 and requires X6 or X7. The problem is that whenever I run X6 after runninx X4, it insists on re-indexing (or something, I don’t have it here in front of me) all my PDFs, which takes forever. I think the X4 and the X6 must do something slightly different with the database files, and they insist on re-doing it to their liking every time i start one up. I do not want to bring all my various machines from X4. Is it possible to have X4 and X6/7 use the same library without re-jiggering the database everytime it starts up?

> no - it isn’t possible. The two versions of endnote index differently so this will happen every time. 

  ok thanks.  Is there any way to get X4 or X5 to work with Apple OS 10.9?

> I am also surprised you haven’t had problems with multiple users and a library on the dropbox, as in my hands, this leads to a disaster and corrupted libraries because of the way endnote handles the additional folders.  It is not recommended. 

  is this just because of simultaneous use?  I only ever have the library open in one place, so synchronization is not an issue (nothing ever gets changed by 2 instances of Endnote at the same time). I’ve been using it for years with X4 on several different machines (bouncing between Endnote on my laptop at home and my desktop at work) and it’s been working perfectly.

    If there is no simultaneous editing of the database, do you still think it’s a problem? Why would there be a problem if X4 running on different machines was adding references to the same folder that just happened to sync via Dropbox?

Yeah, my problem isn’t the licensing - I have the copies, but I don’t like the new version and I was hoping to keep using the older version on the other machine (my plan was spoiled by having to get a new laptop with OS X 10.9 which doesn’t run the older Endnotes…

Maybe I should be using their Sync, I hadn’t been following this feature. Does it keep attachments also (if I upload my library to Sync, will the PDFs go there too?), and is there a limit on size (I have a huge library)?

thanks!