First can I just say, love the ideas! Think the fluff behind both is fantastic and the synergy between them has the potential to be devastating!
As to the lists, I am finding it really hard to choose between the two Night raven lists. But I think I am leaning more towards list B, 25pts extra to get effectively 4 attacks on the charge (plus 1 hammer of wrath) is a bargain.
As for the Dawn Strikers, as much as I would love to say A (heavy bolters are pretty cool), I've got to go for B. The list really does lack anti-air and long ranged anti-tank, something that is helped by the inclusion of this devastator squad. You are benefiting from tank hunter too which is a major bonus. However, these guys will get a fair amount of attention because of this. Hide in the ruins and these guys will do the rest. The Scout squad however seems very odd. I understand why they have been suggested, but in their currently state they are a unit built for combat with no way of getting there. You could infiltrate them or outflank I suppose, but I feel this goes against what you are trying to achieve, a detachment which acts as your anchor, keep the home ground secure while the rest of the army heads up the board. Also, the teleport homer only works on terminators, the locator beacon is what you really wanted.
My suggestion would be:
Then with the remaining points, boost the Devastors up to 10.
Why? Good old "Combat squad" rule. By boosting them up to 10, you can split them into two 5 man units. Put the two flakk launchers together and the other two launchers in the other squad. This allows you to not only target two separate units, but also gives you the chance to fire at flyers with the flakk without wasting the other launchers. The extra bodies are used as extra wounds (or scrubs as I like to call them
). They take the hits so the launchers can keep on firing.
Alternatively, instead of snipers you could just do as you said, CCW and BP, with a meltabomb and use them as a cheap throw away unit which can hurt a vehicle/monstrous creature if need be. They will most likely die but meh, not as if they are the future of the chapter or anything :D