Hosting my own too. There's gmail as backup. But host my mail server, webmail, imap, smtp everthing.

Blocking spam isn't that problem. But making sure your mail goes to the receiver's inbox is.

You can block 90% of the spam by using only reverse DNS lookup -- doesn't match? Reject. 90% of the remaining can blocked using DKIM, SPF checks. No need for ip black hole check or spamassassin training.

The benefit : I can block a sender or his domain in a single click from webmail. Couldn't do that on gmail.