In case you missed the update, yesterday Microsoft released an updated Windows Azure Active Directory DirSync Tool. As detailed at http://social.technet.microsoft.com/wiki/contents/articles/18429.windows-azure-active-directory-sync-tool-version-release-history.aspx you will see that this version is now supported on a domain controller as well as containing a few other fixes detailed on that link.
Regarding the domain controller support, you might also like to check out http://social.technet.microsoft.com/wiki/contents/articles/17370.best-practices-for-deploying-and-managing-the-windows-azure-active-directory-sync-tool.aspx#A11. On this link, you will see that there is an important step to note regarding domain controller support:
“However, the admin installing the tool will need to log-off and log-on again after the Installation Wizard is complete and before the Configuration Wizard is run”
The topic explains why this is required and what you will see if you don’t follow the process.