Yeah, it's true, the black adaptor is slightly better than the built in on the S consoles. The main difference, as pointed out, is it does 5GHZ and 2.4GHZ. This mostly matters if you actually use 5GHZ on your router, or stream a lot of movies from your PC.
The Black Adapter is for support for N Wireless Routers, which is a secure and more faster connection to your router. It costs a lot more but is worth the money, i use it in my house, the signal reaches a fair distance and is great for streaming through
media Center and Playing games. Recommended product.