I don't hold any of those certs, though I do have all the materials from several from personal training to group fitness. I have a degree that includes Anatomy & Physiology, Diet & Nutrition therapy, Pharmacology etc. I have also worked in sports medicine rehab, PT/OT, ortho/nuero surgical, and Cardiac to name a few. I'm a retired nurse. My problem with the certs is I don't need all the numbers involved, ie: BMI, etc. Also the reason I got into pole was because I can't jump, run, or do any of the Cardio type classes like Zumba etc. So for me to try to obtain a cert and the requirements in particular for group fitness of teaching a regular cardio class, with my knee, just isn't going to happen.
I also agree Veena, that there are good instructors out there that are not certified, but are very knowledgeable, and are awesome. I own my studio and teach pole, and don't have any certs other than an Elite Calisthenics Specialist since allot of what we do involves that, and I didn't have to hurt my knee to do it! We also have gyms here that don't require certs for group fitness. They test you to make sure you know what your doing and have you intern for a brief period to make sure you are safe before hiring to teach. Having said that, I'm certainly not against them, but they don't always mean a person is safe because a paper says they passed. :) Good luck with whichever way you decide! :)