[Dovecot] ldap performance?

[Jan-Frode Myklebust]

We're looking at replacing our mysql auth and userdb, with a 
set of Red Hat Directory servers, and I see dovecot supports
either authentication binds, or "password lookups":

    http://wiki.dovecot.org/AuthDatabase/LDAP

I'm curious if anybody can give any insight as to what kind of
performance to expect from authentication binds ? How many
POP3s/second should we expect from it ?

Our directory servers will be 2 blades with 4 cores of 2GHz each,
and we expect to keep the full directory in memory on both servers.


  -jf