Actually the CF-reinforced props are stiffer than the nylon ones. That should yeld different response in some situations for sure, but it´s hard to tell just by flying the P3. I feel the CF ones are slightly quieter but can´t tell any difference in performance to be honest.
Out of pure personal preference (i.e. not for performance) I like to use them when its windy. I also fancy the metal hub ones but those are not CF-reinforced, just the hub is metal. Any DJI prop will be fine, really. I do fly CF (real) props with my other ACs but wouldn´t fly anything else on my P3.
Adding carbon fibers to the plastic mix is a common tecnique in industry, used whenever you want different characteristics in regards to strenght, stiffness, etc. It´s not snake oil or hype, just engineering. Whether or not it affects the performance or by how much is another discussion altogether. But of course that´s the whole purpose. Either way, they don´t cost much more so it´s worth a try if you´re curious.