Just an update (can't edit the last post due to time limit).
I have just tested another download (Ubuntu to be specific that originally was currupt after each attempt) and that has worked fine.
My stats on the modem at the moment after being up for 2 hours and downloading around 1gb are:
Line rate: 14999 kbit/s (2358 up)
That is compared to the thousands of FEC and HEC errors I used to have, as well as a few hundred CRC errors.
Semi positive news so far - just no sign of a speed increase.
Edited by Cyberoonie (Fri 04-Nov-11 12:57:09)