FierceGuppy: For example, 100 people downloading 100GB at 100Mbps is likely to cause more congestion than 100 people downloading 10TB at 20Mbps.
Not quite.
100 people downloading 20 TB per month is roughly 100 x 33Mbps per hour sustained traffic throughout the month. If there were hypothetically 100 customers downloading 10TB that's be 3.3Gbps of traffic just for them, which in itself would cause an impact across a DOCSIS platform.
100 users downloading 100GB per month wouldn't be continuous traffic - even if they were bursting to 100Mbps it would be momentary traffic, not continuous. It's sustained background traffic that's the real killer here - whether that be torrents or somebody watching HD video feeds 24/7
You can't allocate a CIR of 30Mbps per user to sustain that sort of throughput and deliver a service at the sort of price that our unlimited plans are.
You'll see plenty of posts from me last year predicting 2014 would be the year we could start to see price increases for unlimited plans because increased traffic usage wouldn't be sustainable. I think we're a little closer to seeing that actually happen.