To my simple mind, the biggest problem is that there are two potential bottlenecks, the first is the connection speed, and the second is 'bandwidth' of the ISP. By 'bandwidth', I mean contention ratios, congestion, FUPs and traffic shaping.
As regards the ISPs, and taking one example from above, I fully understand why ISPs have to impose traffic shaping. But an ISP who applies traffic-shaping should, in my view, be made to state up-front that the headline 'up to' figure will only be available for some applications, whilst other applications (preferably to be listed in advertisements) will be 'up to' a much lower figure.
For connection speed, my view is that the real problem is lack of accountability. BT seem to have complete freedom to declare what each line is 'capable of', with no means of challenge, unless the householder is lucky enough to be able to demonstrate a voice-line defect. Further, each line's actual connection speed is governed largely by BT's DLM (LLU excepted), and again - BT seem to be responsible to nobody for ensuring that DLM works as efficiently as it can.
