I've been lucky enough to have FTTC for two years now and what started off at 80/20 has slowly slowed down to 65/20. Every time I have a power cut (and there have been a few) 1mb or 2mb is dropped from the speed and it never seems to increase again.
Is it possible to have it reset? Zen seem to think not.
The stats on the line are quite good, details here: http://www.sadandlonely.com/fttc.jpg