Some reminders of other MDT UberBugs out there.
Johan Arwidmark has found been following up with the MDT team on a couple of bugs:
Turns out that if you have an encoded administrator password in your Unattend.xml file (not recommended), then MDT 2013 Update 1 may not reset the <PlainText>False</PlainText> back to True. This can cause a break during Windows Setup. This may have something to do with a change in the ADK from MSXML3 to MSXML6. Microsoft is investigating.
More errors with MSXML3 to MSXML6