About two years ago I tried to used AO3 bookmarking to masterlist a small fandom's works. I set aside the project waiting for bookmark improvements. Filtering will improve things.

However, I say don't rush it. AO3 resources are precious! Fandom will get by on pinboard, which seems to be welcoming (@pinboard recently tweeted that he wanted to attract fans because they were great bookmarkers.) and is dedicated to bookmarking. And diigo isn't too bad for those of us who don't want to give pinboard our credit card details.