I have no affiliation with the people behind Papers, I just use their software and wanted to read my saved articles on the bus.
Although this app does not write to Dropbox, it only downloads and caches the database and PDF files Papers3 stores in Dropbox, I can't guarantee it won't break your Papers3 Library. So although I think it is completely impossible, no guarantees (If something drastic does happen Dropbox has EXCELLENT rollback support anyway).
There are ads, but they can be easily disabled in the settings if you find them irritating.
- No guides, when you first open it, hit refresh, that will prompt a dropbox application access prompt, hit refresh again when it's finished (This is at the top of my list)
- No search
- Portrait layout on tablets is horrible.
- No configuration (beyond Link/Unlink from Dropbox and Disable ads)