I use FTTC with my own DrayTek router. The speed never appears to drop. I see very occasional service dropouts after midnight, which I have put down to BT Openworld rather than iDNet. I run an independent VoIP quite happily. I have never needed to call support. Not the cheapest, but I see no reason to change.
Time With Provider: 8 Years
Package Name: Fibre 40/10 Unlimited