I have both books, and they're quite different from each other. SUS2 is more of a comprehensive list of the facts that you need to know. MTB is a more superficial review, but it really presents things to you in the way that they're likely to be asked on the test. I think MTB alone is enough to get you to pass, but it won't help you with some obscure left-field facts that you need to know to get an above-average score.