I'm not sure what I could offer -- my experience is limited to wrapping my head around EDI file formats + processes, and understanding what would be required to support a small manufacturing company's who directly drop ships their products.

Given the Expense + complexity of EDI, in all cases we've found it more cost effective to integrate with all the alternate Web-based import/export tools provided by systems like VendorNet, or whatever other crazy systems our customers use.

If our volume gets bigger, we'll probably have to revisit that position, but it's served us very well for now.