I posted a support topic, but Winamp appears to be lacking in the default import / export plugin. It's too bad that I discovered Winamp Backup Tool before I found myself encountering an issue (though testing it before switching to a new computer).
The library exporter tool can create .m3u and .csv and .xml files, but it cannot import an .m3u (cannot be added to the "open with" context menu in Windows) or a .csv, so those two are completely pointless (from my knowledge of the software).
What was a simple migration of files to a new computer has become a bit of a problem in that I cannot load all file metadata like Producers, and the files that are added from the .xml file do not work if you have a different drive letter and even after modifying the exported files for the new drive and file location info.
This is more complicated than it needs to be.