Thanks for your suggestions, but Demo Run is a card that wins me games regularly. I will definitely keep it in.
This deck (or its pre-NRE version) won me a GNK and went to top 8 in Regionals. So I tend to assume, I know what I am talking about. In this deck, D4v1d would be nothing but an extremely unsustainable Blue Sun Counter. A mere silver bullet. Not worth it.
APart from that, Blackmail actually is probably the card I discard most of the time (apart from excess Wyldside and similar). In chess the saying goes that the threat is worse than its execution. As long as I can threat the Blackmail, I have reached what I wanted.