I did the Excelsior workshop and passed the CPNE first try with no retakes and I feel like the workshop was an essential part of my passing. I can't speak to the efficacy of the other workshops, but my thought was if was going to take a workshop, who better than with the people who are actually testing me! The main thing here is that no single workshop is going to magically make you pass. You need work your tail off and show up prepared!