This is my personal opinion about SN and what I know is mainly from how people described their last moments in GBTs. It's very mixed from peaceful to violent (especially vomiting/nausea) My major point in comparison to other OD methods is, you are fully conscious until you pass out bc of lack of oxygen (Methemoglobin building up) while with other OD methods you pass out before the actual process of dying starts.
It's certainly not the "new N". However SN is a very effective method if someone can go through with it and has access to the suggested medication to increase success.