I'm about to move our current production environment (5.0.8) to a multi-server environment (5.0.9) starting by creating an LDAP replica and sync it with the master production one.
The question is should I upgrade the production LDAP master first to 5.0.9 before trying to sync the replica?
You can do it any order you wish... But all your servers need to be running the same version.
If your main LDAP is 5.0.8 then your replicate must be 5.0.8.
If you want your replicate to be 5.0.9 then you must upgrade your main to 5.0.9 first.