I recently finished “migrating” my google accounts for PaperPile. With about 8000 references, this was a chore for sure. I followed the method of making shared folder and label folders and one for unsorted. Okay, so perhaps I have not been that diligent at sorting all the time, and there were 5000 references in the unsorted folder. The process took about a week.
The “Add to Library” feature worked okay on folders with less than 200 references… over that it was a bit hit and miss. With 5000 in the unsorted folder I got the messages that either the PaperPile Chrome extension stopped worked and needed to be reloaded, a hang, or completion without importing all of the references.
My feature request is simple here: Allow filtering shared folders by those that are not already in my library… this would save a lot of time and hassle.
In practice, I just kept selecting all and re-importing, but every time I did that it combed over the several thousand that I had already imported in the folder… I was also never quite sure if I got them all.