synchronizing

Hey all,

Is there a module that synchronizes two Drupal sites, migrating nodes created one in the other? My sites are D5 -> D6. I'd like to preserve URL aliases if possible. Mainly I'm synchronizing blogs, with all the related comment/user/node issues. I've seen some ideas out there (Node Export with Node Import), but I'd like to know if anyone has done this simply or has some clever idea.