I don't know any enterprise installations of Mac OS X Server that use AFP.
As for kerberos, that is painful on any platform. At the moment at work I am trying to figure out why Mac OS X takes 10 minutes to connect to a Windows Server 2003 based file share, all I see with Wireshark is a bunch of Kerberos stuff being thrown around, whereas Windows clients connect without issues, but without ever attempting to use Kerberos.