Earlier quoted context omitted.
But the part you curated you can export and take with you.
You can't export the content of the feeds (EDIT: using Google Takeout, that is.) Oftentimes, GR is the only one that still has a copy of an older article. What use is it to know I've starred an article if I can't read it anymore? (To remedy this, I've been using Reeder to export all my starred items to both Instapaper and Evernote. But no thanks to Google.)
Just need a way to do it automatically...