ACE has a tool that allows side by side comparison of various certifying agencies. They, of course, are promoting their own, but it is well constructed and allows comparison across a wide variety of benchmarks:
IDEA has a tool to look at various certifications, although the information seems to be copied from marketing info. of the organizations themselves, rather than to written to take a stand on the relative merits of the organizations:
There is an excellent article from IDEA, more about personal training, but applicable to group ex also, that looks at general issues of training and certifications, which I highly recommend:
To answer your specific question though…. remember this site is not manned specifically by IDEA staff. Sometimes IDEA staff answer here, but it can as easily be an IDEA member. If you want to ask about IDEA policies and recommendations it is probably better to call them and ask the helpful people who answer the phone if they can direct you to the IDEA office that can give you the most definitive answer to this question.
1 800 999 4332