Well I had all weekend to test and it feels like a completely different connection. I've not had a single slow down even at peak times.
Not that the previous one was bad just that it would show max speed sometimes but not all the time and sometimes VOIP calls wouldn't come in with the correct tagging etc.
But it's now exactly as RobertoS described and Kelly and Dave tell us it should be.
Plusnet unlimited FTTC