IMO the only difference between AoL & ntl regarding the CAP or guideline or whatever you want to call it is, ntl have been 'honest' (not sure that's the right word...but hey) enough to put a figure on it (1G/day).
As it stands, AoL's T&Cs can be interpreted any which way they wish, which could mean no limit, 2G, 1G or 0.5G !!!!
All of which doesn't address the real problem which is not bandwidth but congestion at peak periods !!