I took Powerscore. My score went up 14 pts from first diagnostic to test day. The course is not exactly like the bibles. I had the bibles first, and I might have been able to do it myself in LR, but not games. The LG Bible does not have enough examples.
Honestly, I needed someone to walk me through it and then pound it into my head--that's what you get from a course.
Plus, you get soo much more material than is in the bibles. The design is the same, but you get more--and you get people to interact with and help you analyze your mistakes.
I hear testmasters is just as good...but do take a class!