We will be releasing ACMP 6.1 soon. It is in final QA.
We recommend anyone who took the Bootcamps for AOS 6.0 or earlier to take ACMP 5.0. (As you observed, there is no ACMP 6.0) The ACMP 6.1 exam includes new topics such as S3500 basics, Visual RF Plan, and Spectrum analysis. If you are comfortable with those topics, then you may want to take the 6.1 version when it is released. Otherwise, ACMP 5.0 would probably be better.
An ACMP 6.1 study guide will be published soon as well.
Kevin