It would be nice if the postfix config file main.cf were to end with a comment. I guess it is common to place additional custom configuration directives after the gentooish part. Right now the official part ends with readme_directory. Whenever a new release comes along and I ask etc-update to do a side-by-side merge, I get a single change form the old readme with all my customizations to the new readme with no customizations. To get the new readme directory and my customizations, I have to edit the config. If you were to append a comment that stays fixed in future versions, there would be two different changes, so that I can change the readme directory by pressing r and keep my customizations by pressing l. Appending a single "# End of Gentoo configuration, customizations below" to the file in the ebuild should be easy.
i don't really want to customize main.cf since it directly comes from upstream, and that would add more complexity in the ebuild. For your etc-update upgrades work, i suggest you use /usr/sbin/dispatch-conf (provided by portage), which will learn from your changes/nochanges. The next time it will upgrade the readme_directory path without touching your customizations.
