mercutio: i don't think comparing peak time to off peak performance is necessarily a good comparison.
in the past there has been slowness with downloading over http off-peak with some ISP's with transparent proxies that reduce maximum tcp/ip performance for file transfers. (it probably doesn't make much difference for web browsing)
if one isp gives 400kb/sec peak, and 600kb/sec off-peak, and another one gives 1200kb/sec peak, and 3200kb/sec off peak, it may be considered then the second one is obviously better, even if speeds vary. and speeds do vary normally on the internet. sometimes just cancelling and restarting a download can give a better download speed, as some systems alternate routes. (as well as this, tcp/ip can take a long time to recover from packet loss)
the other thing to look out for is US residential peak slow downs, this used to be a common problem with battle.net for instance.
Not sure that your comments make a lot of sense, or am I missing the point?
This comparison uses a simple time comparison because the result is pretty close to a Minimum/Maximum of medians but easier to calculate en-mass.
ISPs use of proxies is the ISP issue, we simply measure the net result on users connections. Unless you represent an ISP?
I very much doubt that ISPs control maximum speeds during off-peak periods, if they do then that would not only show up in median ISP speed / km and it doesn't appear to do that, but also it would cost, for what purpose?.
Cancelling and restarting? Please take a look at our publications, we make around 720 test-runs per probe on over 400 probes each month. Many of these test runs also measure more than one file and we use multiple tests for each hourly median. Restarts may be an important point for a manual test where you run two or three tests, but not with large numbers of tests. eg. Last month we completed 153,000 test downloads of a file in Dallas.