For the record, you’ll only get banned if you do stupid things, including but not limited to the following:
- Downloading illicit CIAs and using them online.
- Blatantly using cheats online.
- Leaving Spotpass > Sending of system information on (with CFW installed)
- Leaving friend list on (with CFW installed)
Please keep in mind that if you install custom firmware of any kind, there is always the risk of being banned. However, there are ways to bypass this, like injecting an alternate LocalFriendSeed_B code.