We use Axway for Managed File Transfer with External Vendors at Costco.
For Outbound interfaces, we encrypt the file using PGP, and then send the file to the Axway Application's Vendor Account using ssh key authentication with the UC4 RA SFTP job (v3.01).
It seems that Axway is optimized for SFTP. Since the external accounts are defined and stored in the Application, connecting via SFTP is the least painful way of transferring the files.
For the Inbound interfaces, the Axway application drops the file on one of our NFS mount points, and we pick it up from there, decrypt it and transfer it to the correct internal interface with a regular UC4 JOBF.