Any enterprises using greylisting on Sendmail / Postfix?

The company I work with has looked into purchasing an IronPort, Symantec 
8160, or possibly a CipherTrust solution (6.0 will have 'greylisting'). They 
all seem to do a 'custom' form of greylisting, but each box has minimal 
functionality. It seems like an enterprise solution should be robust and 
have all the capabilities that the boxes are built with. For example, the 
CipherTrust solution is actually a FreeBSD box, but the shell only has a 
hand full of commands. You don't even get access to chron to set up 
automated backups. I understand that giving extended shell access would 
probably cause a significant increase in helpdesk calls, but is seems that 
an enterprise solution would required this kind of configuration.
 Teo