if I recall correctly, there are quite a few people who did use Univention AD-Takeover succesfully with other Samba/AD installations such as Zentyal:
(there are more topics on this, but they are all german. If you're interested, just search for Zentyal )
Regarding robocopy: You could use a Windows client to robocopy from the CentOS sysvol to the UCS sysvol. If that is no option, rsync should also work but be careful to copy also all file ACLs and extended file attributes.