Send Reading List to Instapaper
I made a tool called Send Reading List to Instapaper. It does just what it says: it sends the unread articles from your Safari Reading List to Instapaper, a multi-platform service that provides a superset of Reading List’s features. Download and more details at GitHub.
Articles are not automatically removed from your Reading List when sent to Instapaper, which may limit its utility as a way to “sync” the two. However, it may be useful if you’ve accumulated a large number of Reading List bookmarks which you’d rather read with Instapaper.