Is it possible to do a search for all checklist items? If so, what character (or character code) would need to be put into the search field?
If this is possible, I can imagine it would be possible to set up a Keyboard Maestro macro to find all checklist items in Agenda, copy them (e.g. at the end of the day) and automatically paste them all into Things 3 at a time of my choosing. Would be pretty great!