One thing I've noticed with some of the prestige classes are the relatively low entry requirements. For example, the Master Inquisitive requires one feat, 6 ranks of Gather Information and Sense Motive and 3 ranks of Search. A bard or rogue could get all of those by 3rd level, and start in on their 4th.
Speaking from a mechanical perspective, isn't that a little low level to be taking a prestige class? Has this been errataed, or did you intend for the requirements to be attainable at a low level?