As I understand Ulrich, the old SLES11 package does not even support the module load directive to be added. That's why I think that his expectation that rolling upgrades with replicated cn=config always just work cannot be met.
Right, because SLES fundamentally changed how slapd is built out. In that scenario, rolling upgrades will not work. This wouldn't work with slapd.conf either, since you'd have to change the slapd.conf configuration too. I.e., nothing specific to cn=config about this, although cn=config does add an additional wrinkle since it can be replicated.
--Quanah -- Quanah Gibson-Mount Product Architect Symas Corporation Packaged, certified, and supported LDAP solutions powered by OpenLDAP: <http://www.symas.com>