My hat is off to you first, for being straightforward about your problem, rather than being a jerk about it as many people do when they have trouble with a product.
Something to consider - it may not be an issue with the throat mic, or your radio - it might be an issue with your throat. Every person is different, and that includes the way their bodies produce sounds. I have a bachelor's degree in radio and television broadcasting, and while in school one of the things I learned was that there isn't one set way to mic a person best. Because of differences in both bodies and speech patterns, different people need to be miced differently to get the best signal quality. While we didn't deal with throat mics for broadcast, the same holds true. There may be a reason that the Firefox mic isn't working with your throat in particular.
I've used both the Firefox and the Iasus throat mics. While I like the earpiece on the Iasus better, and one would expect it to be better with its dual pickups, I get a clearer signal out of the Firefox.
(sound recordings from both are at:
It may really just be an issue that you aren't a person who is a good candidate for throat mics, or it may be that a different model throat mic will work better for you. Have you had any other people try the mic, or tried it with another radio. Position of the pickup is critical, it must be right on the side of the adam's apple.