For many use-cases rsync and scp are not adequate. For example neither can provide a file-listing or interactively walk a tree, which is essential for a wide range of push-based or fileserver-style applications.

rsync can provide file-listings:

jsight@jsight-ubuntudesktop:~$ rsync localhost:/home/jsight/hackernews/ drwxrwxr-x 4096 2012/01/29 20:02:48 . -rw-rw-r-- 0 2012/01/29 20:02:36 tmp1 -rw-rw-r-- 0 2012/01/29 20:02:38 tmp2 -rw-rw-r-- 0 2012/01/29 20:02:39 tmp3 -rw-rw-r-- 11 2012/01/29 20:02:45 tmp4 -rw-rw-r-- 11 2012/01/29 20:02:46 tmp5 -rw-rw-r-- 11 2012/01/29 20:02:48 tmp6

Thanks! That was new to me.

Still, can it also serve as an interactive shell with mkdir, rename etc.? An rsync-based ftp-clone would indeed be my favorite for a replacement.

Maybe you should go with ssh if you need a secure ftp replacement: http://news.ycombinator.com/item?id=3526713