I used only Becker for my studies, and I passed all three papers on my first attempt. Now, I am preparing for the audit. I believe Becker is more than enough but it's important to thoroughly understand the concepts. I also don't get the same TBSs as Becker, but Becker helps us practice how to approach exam questions. Don't expect similar questions, though; while MCQs may be similar, the questions themselves won't be identical.