Well for one.. i love the unlimited mailboxes unlike clarkconnect.... I also like the user interface and the flexibility of this os. Although one thing that would BLOW competition out of the water would be LDAP with Auth... I like to modify things, so if anyone can let me know where the auth scripts are i can maybe modify for ldap with auth.  Also wanted to know if anyone has ways to integrate another spam filter into this. 
SME ROCKS!