One of the many reasons syncing solutions like Dropbox are so popular is due to the fact that they are intelligent enough to know which files are already present on the server and other computer; and only transfer new and changed files. For example, you can copy and paste your Dropbox folder to a totally separate location or a new computer and then link up your Dropbox account to that folder. Dropbox will recognize that the files are all the same and won’t waste bandwidth transferring all the files back and forth.
Recently I was using FTP for a project that involved frequent updates to the server. Maintaining a list of all the files which were modified to transfer them via FTP soon became a problem.