This is immaterial to the "use keys" suggestion. I realize that you mentioned the key+password case, but I can't help but think that the solution to that is simply to go with a key without a password, limit the account on the other end as much as possible and swallow the bitter pill that if they have access to your passwordless private key, they probably have access to far more dangerous things.

In short, this can be solved with proper access restrictions and full key-based authentication, and nothing but bash and scp/sftp.