Does anyone know of a secure ftp client that will upload to multiples servers simultaneously? I need to upload via secure ftp to six mirrors at one time. Currently I have to open six instances of my sftp client and upload a copy to each of any file that I have changed.
Yes - the sftp client that comes packaged with any Linux distribution.
You can write as many commands as you want into a shell script file.
If you really do need to do the transfers simultaneously, and you are running on Linux (or some other Unix-like OS) you can easily run each command in "background" using "&" as the last character of each line.
It is so much easier to use a Linux machine to manage your sites, than to have to constantly look for specialized Windows clients to do things that are everyday-routine in Linux using tools that come with the OS.