After giving it some more thought. Im changing my mind and vote. Allow everything. All IA s, all supplements, all data sheets, codexes, escalation, and stronghold. If you look at the big picture it will probably balance things out better. As it stands with standard 40k, the game is overall poorly balanced. especially for competitive play. All the new add-ons bring variety to the game and level the playing field for those substandard armies that either need an update or got a crappy update(DA, Chaos). Will some players try to abuse the stuff? Yes but they already do that with standard 40k so thats not gonna change. most players ive seen at tournaments bring fun or fluffy lists and I dont think that would change either.