Oh well, I guess I spoke to soon. Since I last commented on the removal of interleaving by BTw, speed continues to drop and noise margins have gone haywire. In fact donwload speeds are lower than before this whole sorry saga started. So I am now wondering why the interleaving was removed without even notifying users? So to sum up, in rural areas where you are some distance from the exchange my impression is that it is worth putting up with slightly reduced speeds with interleaving but have a much more stable connection.
Hmm… me thinks I will have to hassle my ISP!!