If Chorus America intends to use CiviMail and MailChimp concurrently for a sustained period, automating syncs is advisable. The MailChimp Sync Extension provides an impressive set of features, including two-way syncing, based on system events as well as schedule (or on-demand). The technical documentation suggests the extension complies with the recommendations above, though confirming this through user testing is advised.

Updated: 3-21-2019