I don't think Powerscore's approach is drastically different from ours. Some of my students have benefited from supplementing with the Powerscore book, but when they say "I learned ___ from the Powerscore book," I'll typically find that it's something that we taught them, too! If the book helps you to see CR in a new way, then great. The only danger is that you're renaming ideas that you already had names for, and that might not be an efficient use of your time.
The best thing you can do is carefully review each completed CR problem before checking the answer. What was the question asking for? What did you need to understand about the argument? Were you able to predict an answer in advance? (This should often be the case.) Can you explain why each answer choice is right or wrong?