I’ve waited for a while for someone else to come up with a solution to this, and finally took matters into my own hands.
I’ve rewritten the export tool in WordPress to support BlogML instead of the WXR format. It’s pretty straightforward: you just replace one admin file, and it doesn’t mess with your theme.
You can download this tool at http://www.codeplex.com/BlogML/Release/ProjectReleases.aspx
