I am in a transition process to completely give up on Mac OS X as a server environment.
I moved all my email over to a linux box.
I will move named and dhcp over there soon.
I will keep the OS X server for a little while for AFP and mobile sync. Of course, if I ever upgrade my macbook to ML, mobile sync will die. At that point, I will probably just use smb or nfs for files and forget about mobile sync altogether. Mobil sync was a bear to setup in the first place, and is useless except for documents. I tried sync my photo library, and any change to iPhoto required the whole library to be synced!