Hi,
It may depend on what the problem you're trying to solve is. Do you need full FTP functionality or just a simple way to securely copy files between servers.
I use openSSH, but not SFTP. At the moment I run under Linux so ssh is straight out the box. However, when I transfer to Windows for Jade 7, I plan using cygwin (see cygwin.com) which will give me openSSH, openSSL and literally hundreds of other Linux style tools and capabilities.
To copy between servers, I use scp (secure copy) which is in the same family as ssh and connects to ssh on the remote server to to the secure transfer. To avoid having passwords in scripts etc I use certificates created via openSSL to authenticate. See
http://www.linuxjournal.com/article/8600 for easy to follow instructions on how to do this.
I initiate scp from the command line or via node.createExternalProcess in Jade. Just tried scp on my WIndows laptop (with cygwin installed) and it is available so this may solve your problem. Works fine for me.
Brendan