As such a heavy user of bookmarks that I pay cash money for a 3rd party bookmark manager: literally any improvements would be great. The built-in bookmark managers of browsers - especially mobile ones - are incredibly anemic.

EDIT: The bookmark manager I pay for is called Linkman - http://www.outertech.com/en/bookmark-manager. I first bought it around 10 years ago and still use an old version, so unfortunately I'm neither up-to-date with its present capabilities nor the current landscape of 3rd party bookmark managers.