I read the article and the follow up posts and I wonder if we are all using the same definition for "speed" here. The article seems to imply you don't get 6 Mbps on your DSL line in summer because the copper is hotter and it's harder to push electrons down the link. That is clearly BS, the clock is ticking six million times per second, period.
Are you trying to say that the *actual* DSL speed, as synchronised between the modems at either end, is neither a) affected by the physical characteristics of the copper pair, nor b) variable? I agree the article is woolly between line-speed, throughput, goodput, congestion, etc, but to say that DSL line speed is in any way fixed in the same way that Ethernet or PDH / SDH lines are is contrary to every DSL platform I've worked with. (Also, 6Mb/s DSL doesn't equate to 6 million ticks per second in anything relating to pushing electrons onto the wire. Remember, it's modem technology, just faster - your baud rate is still much lower than your bps.) Regards, Tim.