The BizTalk Server 2004 FTP adapter offers a 'guaranteed delivery' feature, the details of which are not documented by Microsoft. This feature is easy to use. There are problems, however...
There are problems with the current release of BizTalk Server 2004 when you try to use the mapper for complex transforms. And anyway, the XSLT it produces is not good! Uxs 'raw' XSLT instead.