I only have two issues, which I would further research, with verm-X which is the ingredient of peppermint and cayenne.
Peppermint and mints in general are not usually good for birds. There is an ingredient in them which causes burning of the esophogus over time...
and
Cayenne. While it is not dangerous in small quanities, it does raise the body temperature. Therefore, I would not use it hot climates like the South or in the summer. The heavy breeds, which many people have, need to keep their body temperature down in the high heat, not have it elevated. They are very susceptible to heat stroke and dehrydation in the hot weather (susteained temps above 80). Chickens do best in temps of 50 - 70 degrees. As you are in Florida (as a native floridian I know the heat down there, albeit it is not that bad where you are) I would not use anything with Cayenne in it.
While all natural products are more preferred, they are less effective usually in the immediate. Over long term use, they be more beneficial for the overall health and avoidance of chemicals. However, I would not recommend anyone rely solely on a product like that or straight DE, if there are worms or a high probability of them.
Well that is my thoughts on it. I will do more research on the mints with chickens specifically versus other birds.