This plugin allows you to sync local and remote media uploads, theme files, and plugins folders with one click via FTP. Do all your development on your localhost, initiate a sync whenever you need to from the FTP Sync options page.
FTP Sync can only be used from your localhost. If you try to use it from your development server you will get a message reminding you that you are not on your localhost. Also, an admin bar link will be on your localhost copy but not on your development server admin bar.
*IMPORTANT: Setup your local site's wp-config.php to use your remote site's database. Add your IP address (What is my IP?) to the "Remote Database Access Hosts" in cPanel so you every time you sync your files even the database will match up with everything (since it's the same database!).