Here's my take(I've not sat the CAT test but understand the principles).
While I've only sat Security+ in 2004, the big difference I think with the Security+, CEH and CCNP is that they are all more about getting the definite correct answers(what is X, how would you do Y etc), the CISSP is more slippery in that often there are perhaps three viable answers and it's asking you to digest the info and select the most correct/least wrong answer. Thinking vs doing. The CAT format adds a dimension of urgency perhaps and it means getting the basics right is very important, but you can offset that against the previous six hour cognitive endurance test. It also has to be noted(IMHO) that the CISSP is easier on native English speakers, reading comprehension and diligent parsing is essential).
However the exams are prepared is a very structured way, and it is a metric, so I'd counter your last statement by saying the only objective measure of the experience, knowledge, preparation and dare I say it composure on the day(watch the movie 'Cool Hand Luke' or similar the night before) - is whether or not it's passed. I realize this is not comforting, but it is meant to be a good test of the candidate and it will tell you where you have more work to do based on the questions you answered. So best of luck with the next one, and when you pass it is at least good in that it's an exam that is failed regularly because it is a true test.
