I am new to ZImbra and still am not sure if I should disturb my working email system (postfix/dovecot), ldap, mailscanner(SA, calmav) to Zimbra.

I have a master Ldap address book I would like to migrate to Zimbra. I would like to have the same date available to all users. I am not sure how well this would work in GAL vs shared address lists between individual accounts. Any suggestions on migrating and organizing my contacts for group use would be appreciated.