Cool, so they cannot find my by my ip adress or something as like the wii ???
There is no way for Nintendo to "detect" you playing ROMs on your DS, nor is there a way for them to see Wii softmods and backup discs. Nor is there a way they can ban you from using wifi, its not like Xbox Live. Of course any time you connect to anything on the internet they will see your IP address, but there is nothing they can do with that information. So its perfectly safe.