Hi,
I use a linux root server with "private key file" + passhprase for my projects. The user root have no login with password(security reason). Login with file+passphrase working fine in windows with winscp and putty. I have for testing download cwrsync and use this command:
rsync -av -e "ssh -i /cygdrive/c/auth.ppk" root@remote-ip:/folder/ /cygwin/c/folder
"C:\auth.ppk" is my years old file for login with putty. With this command, I get this:
Enter passphrase for key '/cygdrive/c/auth.ppk':