We currently use an on-site server with Active Directory and dirsync to sync our AD to Office 365. We are looking to upgrade from Server 2003 to Server 2012. This server is also our domain controller. We only have around 25 to 30 clients, but we would like to migrate and not re-build from scratch.
So far I've found this guide in order to migrate the DC from Server 2003 to Server 2012, http://blogs.technet.com/b/canitpro/archive/2013/05/05/step-by-step-adding-a-windows-server-2012-domain-controller-to-an-existing-windows-2003-network.aspx
What other requirements would we need to know in order to transfer our Domain Controller from Server 2003 to 2012 in an Office 365 environment? I just want to make sure we aren't leaving any crucial steps out. Also, we aren't upgrading from Server 2003 to 2012 on the same server, we currently have a separate server with Server 2012 installed.