I have not yet worked with accessing an LDAP database (although that may change with in an upcoming project), but chapter 6 of Perl for System Administration compares the use of Net::LDAP and Mozilla::LDAP (a.k.a. PerlLDAP), and discusses some of the advantages of each.

I hope this helps somewhat, and I hope that those more familiar with using LDAP from perl will chime in as well.