For me (a seasoned coder when I took it), the reimbursement was really the part I had difficulty retaining--mostly because I've always been a coder or reviewing from the coding perspective. Anyhow, you'll do well on it since you're already in the business and on that end of the perspective. Despite that I worked on the payer side just prior to taking it, I didn't deal with claims processing as much as program integrity audits, medical review (more coding focussed tasks). Regardless, the ICD Chapters section of the exam was probably the most challenging, making you analyze the reported procedure and diagnsosis. I'm sure this is something you could do though, based on what you've said about your work.
Just be sure you can code out of both CPT and ICD procedures section and you know your coding guidelines for ICD Diagnoses codes and you should do fine.
Don't freak out and doubt yourself, just try to retain the information you study.
Good luck again and let me know how you do.