Nice!!!! Definitely giving this a whirl!
The only features I need in LDAP
* One-way (master->RO) Replication
* Standards compliance for queries/binds
* Easy authentication for setup/administration
* Add additional schemas (For instance, the SSH Key schema)
OpenLDAP definitely makes all the above quite difficult, but it's doable.
One esoteric feature we use of OpenLDAP is SASL delegation. This allows us to defer some users to Active Directory. Nice party trick.