In regards to Nuclear craft I don't understand how it fully works and would not be able to do it justice just yet. As well as parts of it not being complete and mentioned earlier.
I think you're right along the AE lines. Perhaps only certain aspects of that will be harder to get to. The pack will include some adventure but no story. I aim to do this by allowing the player to the craft harder recipes with items they pick up on their travels to make the recipe easier. I have tried to make Big Reactors more complicated in the creating stage but there is nothing I can do about the running of it.
Perhaps make some of the automative aspects of AE expensive, while keeping the storage system relatively cheap? Also what do you plan to do about the pure certus time gate?
One more thing, I had the idea of making rails cheap and easy, while making pipes a little more expensive, to make rails for useful for long range systems.