Auditing is a systematic, independent and documented process for obtaining audit evidence and objectively assessing it to determine the extent to which the audit criteria have been met.

Because of my experience as a lead auditor, I know very well what CIs look for. This gives you confidence in an effective implementation of the various audits.
I answer your questions, something a CB may not do. This gives you insight into the effectiveness of your management system.
Finally, I ensure that the discussions take place in a pleasant atmosphere and add value. This has proven to be an additional advantage.