You can use TCP LEDBAT to keep background downloads fair even with multiple connections. OS X does this for large downloads and software updates, and BitTorrent kinda uses it to not kill your net connection.
It still has some issues when multiple machines download the same update, maybe this is when you home sysadmins could start running a caching server?
It still has some issues when multiple machines download the same update, maybe this is when you home sysadmins could start running a caching server?