Recently, I was involved in the migration of the infrastructure for one of the large clients of the company I work. Apart from the regular tasks, I was entrusted with one of the important migration activities., the SCM.
We use both Subversion and GIT based on use case and practicality. At the end, I had migrated around 23 repositories, most of them being Subversion. And, migrating and replicating subversion has its own quirks and is not very straightforward.
The following links helped me a lot to figure my way around the replication, migration and debugging issues around it.
http://dynamicproxy.livejournal.com/58569.html
http://stackoverflow.com/questions/2219455/subversion-is-there-anything-faster-than-svnsync
http://serverfault.com/questions/175437/subversion-cant-move-permission-denied
http://serverfault.com/questions/248495/svn-error-rep-repository-uuid-xxx-doesnt-match-expected-xx
http://gregoire.org/2008/09/03/fun-with-svnsync-and-googlecode/