CentOs directory server is a more stable implementation than Fedora DS. i find FDS crashes alot more, as do Fedora servers in general.
http://sangacollins.wordpress.com/posts/centos/directory-server/this is a link to the guide our company uses to create new LDAP + Samba domain controllers for our clients. we are in the middle of deploying 34 sites so this guide works perfectly if you follow it closely.
please note, Fedora DS, Centos DS and Redhat DS are all the same thing, just different branding. and slight differences in the environment.