Bidirectional rsync flaws

rsync does a fantastic job to sync and keep in sync content from one to another system. Backups are perfect with it, use rsnapshot to get even more out of it.
But rsync is not good in bi-directional syncing in the case of deletion of content. Despite, that you can delete all file on all content directories on all hosts, which is not an option for a the very-day user.
Keep in mind, that you need same timezones and synced clocks, when using the –update option

Look out to keep things in sync, with deletion too, take “unison” for example.