RBrowser combines all the secure tools available on both the local and the remote system. The SFTP, SSH, PAX, the Bourne Shell, and SCP clients are all part of OSX. Other UNIX systems do not have pax but have the rest. Each have their strong points and their limitations as well. SFTP is better for file transfers because unlike scp it can hold a continuous connection and create links. Ditto is used if both hosts are macs, so fork data is preserved during file transfers. SSH is used for file operations on the remote hosts, since SFTP has major limitations: for example it cannot make a copy of a file from on folder to another on the remote host! Also, SFTP does everything file-by-file, which takes a long time if it operates on a big file system. ssh, using a remote shell can do recursive file operations like rm, chmod very fast. Direct remote-to-remote operations require SCP. RBrowser automatically selects the best available tool for the job, so you do not even have to think about it!