Been using both major brands for over 10 years now and swear by it. I very seldom get busted even when the wind blows right at the game. There is no way to be completely scent free but we can do many things to minimize it. That being said, carbon clothes are just ONE part of keeping scent free or almost scent free.
You still gotta be clean, use the wind, use scent sheild or another spray especially on your boots, you gotta avoid sweating up as much as possible,and you have to stay away from anything that could taint your clothing like food, smoke or car exhaust.

Carbon clothing is a part of the puzzle, not the whole picture.