I think it also depends on how much you take, basically on how fast you get sufficient levels of it it in your blood. That's why the recommended dose is 25g, which is about 10 times the lethal dose. But increasing the amount you take also leads to an increased risk of vomiting. Idk, one of the things that makes me anxious when thinking about SN suicide is the number of variables involved.
Oh, and regarding the use of benzos to speed up the process of losing consciousness. Does anyone know if overdosing on Zolpidem would also do the job if I can't get my hands on more benzos (I don't have enough to OD on)?