Some Sideboards now show Godhead of Awe. I not sure that's a good Sideboard choice. It doesn't weaken the fast aggo Decks as far as i know. Against which Decks you would use it?
Why do people play the 4th Pact of Negation in the SB and not dispel?
The fact that pact is "free" gives it a huge advantage over dispel. For example, it allows you to roll out an unlife on t3 and still have the ability to counter something. As far as paying for pact, often times you will just win on top of the pact trigger, and if not, angels grace in response to the pact trigger. Another big advantage of running a 4th pact over dispel is that it gives you better odds at not killing yourself if you need to spoils for pact.
deaths shadow
The fact that pact is "free" gives it a huge advantage over dispel. For example, it allows you to roll out an unlife on t3 and still have the ability to counter something. As far as paying for pact, often times you will just win on top of the pact trigger, and if not, angels grace in response to the pact trigger. Another big advantage of running a 4th pact over dispel is that it gives you better odds at not killing yourself if you need to spoils for pact.