Twitter entries cleaned up and reposted. Whatever the caching issue is that intermittently delays individual entry page updates seems to be affecting the site but whatever the entries are correct in the DB, which means, I think, that they are also correct in the WXR.
(NOTE: This was the final entry written and posted in Movable Type. It retains the MT post ID and is addressable via a WP URL that incorporates the post ID, http://michael.whybark.com/?p=6759 at this stage on the deployment domain.)