lucky015:

tonyhughes:

lucky015: And it is often mentioned time and time again that it is the large scale peak network congestion that causes most of the costs incurred by ISP's rather than the data downloaded over a fairly long period of time while capped.

First point is very valid, but also not to underestimate the second. 

Ah, Yes, What I had in mind at the time of writing was that perhaps 10gb used over time costs them FAR less than the sudden 10GB used by someone buying it at $2 a gb at full speed using it in a couple of hours (Think downloading a steam game)