Has anyone taken a pieper bar preparation course or ameribar? What are the pros and cons?

Ive heard the best prep courses are barbri and kaplan...

Have a look at

http://www.llm-guide.com/board/96419
http://www.llm-guide.com/board/7990 and
http://www.llm-guide.com/board/120

Ameribar and pieper bar exams have been discussed before.