Switched to Pulse8 (standard copper wire) a few months ago from the Phone Co-op. Both piggyback the TalkTalk network but the difference is night and day. I had constant stability problems with the Phone Co-op for years, and a number of times I was bumped down to slower standard ADSL from ADSL2 (but I am close enough to the exchange to benefit from ADSL2). Querying this was a pain as while the initial customer service was ok the tech support you get passed to was difficult and often dismissive.

The switch to Pulse6 was painless (on their silver ADSL package), stability is rock solid and speed has increased significantly (I have used my Billion 7800dxl modem/router for both providers).

I have also found their support to be excellent too, emails answered in seconds and a recent problem where I accidentally damaged my external phone line resolved by an Openreach visit within 24 hours, followed by Paulse8 contact to make sure everything was fixed and working ok. Can't recommend them enough!