if bricking is your worry, there's almost no way to brick, and if you were to somehow brick, there are ways to fix it. with a9lh, brick risks were high due to not apps not verifying things. now, both b9s and nand backups contain a sha file to verify before install. another problem with a9lh was that it wouldn't verify if a system was an old or new 3ds when installing, so using the wrong one would cause a brick. that is no longer the case.
I don't know about getting banned. I always assumed I was, but it's been said that it's difficult to get caught on the 3ds unless you were to play a game early.