My intuition tells me that SN is more peaceful, the vast majority of the time, than people realize here. Of course there is some discomfort, but it's very tolerable discomfort considering the desired outcome is ending your life. I think as long as you know what you're getting into and what reactions are normal, it won't be so bad.
Nasty chlorine, salty, chemical, rubber taste… burning on the way down. Nausea, nervousness, anxiety, palms sweating, overall sick feeling, possible stomach pains. Hyperventilate, shortness of breath with heart beating so fast you think it will explode, dizzy, lightheaded… then pass out.. the rest takes care of itself as long as you aren't found.