I changed to BT when I moved to a smaller property. At first I was told that I couldn't have a dish because it was a listed building. After I moved in, however I learnt that I, was allowed one it just had to be on the side of the building..
I have BT Youview and I'm quite happy with it. I'm not into Sports though my whole package - unlimited broadband, phone and Youview works out about £20/month cheaper than I was paying for, Sky.
The only way I recognise a "lag" I see if I'm Facetiming my daughter and she has the same programme on as, me. You wouldn't notice it at all. Why would you?
No problems with the service from BT so far. I hear their Sports package is very good.