I only have a few small-ish mail servers under my care, and I couldn't agree more.
Reviewing the history of the mailop list [1] shows how frustrating it can be when a behemoth (AOL, MS, etc.) stops accepting your mail. It's bad enough when you're a sizeable mail operation; as a tiny standalone mailserver, you are not at all a priority, and it's possible you'll lose the ability to communicate with a significant fraction of the Internet's email users (regardless of how complete/correct your configuration) and with little recourse.