was designed to replace the old sftp and ssh module. You can ask the SSH experts on the maillist at ssh-sftp-perl maillist
for all the details. The switch started about 10 years ago, and at the time the most important reason was to eliminate the numerous math library dependencies , like Math::Pari
which was an installation hassle, and often resulted in sftp dropping back to very slow pure Perl math processing. It also brought all of the various ssh utilities, like sftp, scp, ssh under one module. I've found it easy to install and use, as it only requires libssh2 to be installed with it's development headers.