Hamish, there's a few changes that can be made for torrenting to have less of an impact on the network. It can be limited to off-peak times, it can be banned outright, or clients can be configured to open less connections and significantly throttle data. In my case, the connection's upstream throughput was saturated by careless seeding. I've helped people configure their clients so that they open significantly less connections (<1% of what they used to, in some cases!) and so that outgoing data has global caps within the client (usually 1 KB/s max). I've also adjusted the clients to run on-demand instead of at system startup.

The downstream data rate is fine for servicing this many people, even if downloads do take a while. It's more than adequate for gaming or streaming at decent quality rates. The biggest issue is that upload is limited to ~700-800 Kbps, which simply isn't enough for this many people on the network, especially if anybody is streaming, seeding, or video chatting. I imagine that there will still be a considerable boost after the VDSL upgrade primarily because of the far more sufficient upload bandwidth.