A somewhat tough question to answer as hardly anybody takes classes from 2 providers at once, so it’s hard to compare their relative merits.
For what it’s worth I took Nathan’s classes at NYSSA for Levels I, II and III. I passed all 3 levels in less than 2 years, and I give him a LOT of credit for that. I strongly doubt I could have done it so quickly without him: the man probably saved me one or two years of studies.
By the end of the day obviously there is only so much Nathan or any instructor can do: only you can read the materials; only you can take the practice tests; only you knows how you study best. An instructor - no matter how good - can only do so much for you, but he can give you a grasp of the exam format and help you identify and retain the most salient points of the curriculum, and Nathan does that very effectively IMO. He definitely helped me stay on track and made me feel more confident that I knew what I was studying toward. And he’s got a good sense of humor and brutal honesty - I needed both…