Here is the question: https://askubuntu.com/questions/504413/what-is-the-fastest-two-way-sync-framework-available-on-ubuntu
I would like to post as an answer, WHY rsync should NOT be considered. The reason why I would like to do this, is because people who are researching sync solutions on Ubuntu will likely consider RSync. This will help them narrow their search.
Would this be acceptable on the Ubuntu Stack Exchange?