I guess we are going over the top again with expecting the ruleset of the saga server will be anything different than the live servers.
Of course it would be awesome to have it limited to the old world, without turan and khitai and dragonspine! I actually do not really care about AAs, meaning disabeling them would be very fine with me. If you can play a class you can do so and have fun with it with or without AAs, every class ist still working and playable without them. And who thinks of AAs when it comes to the old world...
Even if no content is blocked on this server, the idea of at least trying to give evenyone the same condtitions will be crucial. Claims and veteran tokens, depending on the missions the 30% higher exp gain for subscribers, and of course the power items from the item shop.