Hi,
Release notes [1] for latest version of SVN 1.4 mention new
utility - svnsync:
"This tool provides the ability to replicate history from one
repository to another."
May be it will be useful for migration process.
[1] http://subversion.tigris.org/svn_1.4_releasenotes.html
--
Mateusz Loskot
http://mateusz.loskot.net