The problem with transfers via SSH is they are very slow, much slower than the write speed of the SDHC cards. Having a FTP server running on the tablet, would get rid of this limitation.

Yes FTP is more insecure, but only if the login credentials are intercepted, and on a private LAN, it is a very good solution for file transfers. I am actually surprised it does not come as part of the OS and nobody has compiled it.