Arcane Disciple also has the problem that the feat explicitly only lets you cast one AD domain spell of each level per day. Unless you pick up an all-day buff with it, AD isn't going to be solving any versatility problems in combat anytime soon. The feat is best used in my opinion for either utility spells (Desecrate, Magic Circle, and Awaken Undead for dread necros) or shenanigans (adding to the list of Shadowcraftable spells, meeting odd entry reqs, and so on).