Command line FTP is a reliable tool for transferring files.
Command line FTP allows you to transfer files between the servers via the Internet backbone. This means that the transfer will take place very quickly, and will not use your modem connection at all.
You can also use it for testing when troubleshooting problems with i.e. Dreamweaver.
if you use the command line or not, it'll always use an internet backbone and it will always use your internet connection whatever that may be to upload files. filezilla is my fave ftp client with support for pausing and resuming transfers and then there's the fireftp extension for firefox which can be useful, but it has it's time and place.
I also have filezilla installed. I haven't used it yet however. It takes me awhile to understand these these technologies so it takes me awhile to get up my confidence to use them.