I think it makes a lot of sense to add the alien archive/monster manual first, as the drag and drop functionality from those is much more frequently used (especially by the party purchasing it). I'll say that, for me, the vast majority of encounters in Dead Suns used monsters from Dead Suns specifically, so when running that, the Alien Archive would not have been much help. One possible method, which I didn't try, and which may require pro to utilize, would be to make a game with the old HUD sheet, use the importer on your Dead Suns NPCs, and then transmogrify it over to the official sheet game. I'm just not sure how compatible the old HUD sheet characters are with the official sheet now. They seemed to copy over fine initially, but lots of changes have happened since.