Swapped from Sky Fibre Pro to BT's 52/10 package, sync'd at full 55/10 in router.
Edit: I moaned last week about poor YouTube speeds and buffering since switching to BT. This seems to of improved this week and haven't had any buffering issues (touch wood).
This is what I used to get with my old Sky Pro up to 78Mb package, so not much worse off. Except the upload which doesn't bother me at this moment...
Annoyingly vectoring dragged my speeds down from when I first got FTTC back in November 2014. This is what I got back then before everyone else jumped on my cabinet.