I didn't found traces of it searching in the Forum and the Wiki, but wouldn't IP multicast speed up the file transfer?
I'm not expert in Internet Protocol, but for that I know, multicast makes you able to send the same data to more than one recipient in only a packet. With multicast I could send the same file to more client requesting it using the same bandwidth as only one client. Or maybe I don't know what IP multicasting really is.....