Having completed my exams using the Air Pilots Manual Series I think the confuser is a must, since it helps you understand the type of questions you will get and that familiarity saves time in the exam.
(Although not directly related to the question) I recommend for the Nav exam that you practice finding locations on the chart using the latitude and longitude scales. I overlooked this, and since I wasn't fluent at it spent 10 minutes of shear panic trying to find the required locations, without which the whole exam is a no go. I know its a basic thing but not necessarily easy when the nerves have cut in at the start of the exam.
A friend of mine had exactly the same experience.