There is no need to move to different ftp server or
reconfigure to deal with a different directory structure,
continue to run a single instance ftp server which
serves data from it’s own chroot copies.
The problem appears to be that they want to set up the FTP server so
its directories or maybe files are symlinked to files in other
directories arranged in other ways. There are new files available for
FTP every day since it's one of the ways to retrieve RFCs and IDs.
I have to say that no symlinks at all strikes me as the kind of design
you get from security amateurs ("someone might use this useful feature
wrong, so we won't let anyone use it.") There are perfectly good FTP
servers without that problem, which would involve a one time switching
cost that I doubt would be very great.
If we are going to continue to support FTP, it would be reasonable to
use a server that can do FTP over TLS, since it that is something
actually defined in RFCs and implemented in clients.
R's,
John