I'm not trying to convince you that active ftp is better for you - I have neither the time nor the desire to do an analysis of your needs.
I don't agree that passive ftp is any easier to use - BUT - in my experience it's a heck of a lot easier to set up - and, by the way, IE works just great with active ftp, just as you describe it - send them a link, they click, connect and download - with NO changes to the browser, and no tricky configuration at the server.