Hah:

• 2018-12 at the dawn of the Slack (You have to read upwards from there; we weren't disciplined about using threads back then.).
• 2019-05 Steve Krouse's note.
• 2020-04 survey with a question on the subject.
• 2024-06 (100+ comments!) conclusion.
• 2026-05 trying out Colibri on ATProto.