Future sysupdates
When new sysupdates are released, the yls8.mtheall.com site will automatically determine all of the new version values to use with network services. This may take a little while after sysupdate release to finish, hence the server will return error messages until it's done(which is at the same time that the updatedetails text for the ninupdates report becomes available). When that happens you can use the cached server_config.xml, but that's really only useful if you want to use network services which don't require the new version values immediately(which is mainly/only(?) the nasc friends-server, also used with online play, mainly when friends-server wasn't accessible on your system pre-sysupdate to begin with).
Network-request changes(more than just version values) with network services in the future may cause using those network services with ctr-httpwn to break. This can't be handled automatically at sysupdate release. Depending on what changes, a ctr-httpwn update for those future changes may be required, if just updating the xml isn't enough.