Hi nicolas,
copying the whole ColourThatSite\css folder and the ColourThatSite.sqlite Database should normally clone the whole contents. You will have to restart the browser after the copy though, perhaps this was the problem in this case. (Ideally you copy all contents while the target browser is not running).
About syncing: I will consider that. I am also loosely planning an optional online service for sharing colour edits which could as well be used for re-using own edits.
And by the way: Happy Christmas/Holidays & New Year to all!