I have 7 Domain Controllers across 5 sites running either Server 2003 or 2008. In my HQ, I have 2 Servers running server 2008 Enterprise that are domain controllers. I would like to start by demoting one of these servers from being a DC, Reformat it and do a clean install of Server 2012 then promote to DC. Also, name it with the previous name. Once that is complete, I would do the same with the other server. The end result would be both DC's in my HQ are running 2012. I would then be able to start addressing branch offices.
Aside from running the Add/Remove roles under server manager and removing the AD role, is there anything I should be aware of? I would assume wait sometime for all the other sites to realize the DC has been removed before adding the 2012 DC with the same name.