Im not even sure if Opera can upload to ftp within browser.
I know both opera and firefox can download and browse ftp server, (fireftp, an extension for firefox can turn it into a ftp app). Only Seamonkey can upload to ftp server within browsers by default, one file at a time.
Safari isn't famous for its functionality, you can file a feedback to apple, see if they will add it in next version, I guess browsing ftp should come first if not together with uploading, if there will ever be such a plan.