I upgrade to 1.6+ (24.06.06). When I'm migrating database (ru) I have some problems:
1. Described in http://moodle.org/mod/forum/discuss.php?d=48264
2. Category names didn't convert to utf-8
3. Problems with modification lang. I had ru_local. Not all users and courses name has been converting. As far as I now it was fixed...