Everyone here hit on the main points. The products are made from the same code base so usually you only face minor schema changes. If you directory is small you can usually use the ldapsearch and ldapmodify command line tools. Some entire corporate directories are less then 4000 entries and export in less then a second. They import in less then 1 minute. I suggest exporting the data using an ldapsearch and try to load it on a fresh system using ldapmodify/add. The tools will stop on a schema violation and you investigate why that particular object did not load. What you are facing now is similar to a situation you may face with an upgrade from mysql 3.0 upgrade to mysql 5.0. It might be hard to find an upgrade path from vendor documentation, but a plain old mysqldump/mysqlimport will likely work. As mentioned you may have to specifically deal with acls, roles, replication agreements- but you would likely want to add those by hand so you can audit them in the process.
