Filters used (Q: "Do people use the filter options? Do they always switch to a particular one (which could be default then)").
Should be an ARRAY with STRING or possibly an ARRAY with OBJECTS with STRING and relative timestamp as INTEGER
Just as an idea: We currently set defaults for the filters (show both/only me as well as display/hide unchanged text) based on our assumptions about user needs. We could randomize the defaults and then measure how often people keep them. It would need in-which-group-is-the-user-cookie.