I am about a week away from sending off my materials to Essentrics for the Level one certification! I'm teaching my apprentice classes through the wellness program at work, and it is getting very good feedback!
I've thought about doing the Zumba "training", but I too decided I'd rather do Zumba than teach it.
I taught an aerobics and toning class for nearly 10 years - from about 1990 to 2000.