According to the analysis by Mike Kuketz (https://www.kuketz-blog.de/wot-addon-wie-ein-browser-addon-seine-nutzer-ausspaeht/), the (most?) problematic commit is of 2015-04-20 (https://github.com/mywot/firefox-xul/commit/0df107cae8ac18901bd665acace4b369c244a3f9).
This would mean, that users of stable were less (not?) affected. I would remove the plugin anyway, just because of "trust issues". -- Teacher: "Now, if give you five apples, and then take three of them away, what are you left with?" Pupil: "Trust issues."
