Yes you will get banned sooner or later. It can happen instantly, in a couple of weeks or after a few months. Remember that "modding" means just running anything that's not officially supported by Greedtendo. Plus, you are not missing anything by not going online. Should you need to go online, then have a second console for legit things.
Well, best answer I can give you is to follow every guide carefully and don't skip any step suggested there. A mod here said once that people should not have to worry about eFuses if you don't plan to downgrade later to an older FW, and that's what I did.
