My overall conclusion of the SN method...
The PPH is wrong and misleading about a few things.
If you take the right amount, the right purity, a couple of precautions, and don't get any medical help I'd probably give it a 9.5 for reliability.
As far as peacefulness and quickness goes (If you follow the PPH's regiment) it's hard to say because there is only one real case study about this that has been reported in the PPEH that I am aware of. It was of a person who only weighed 100 lbs. and was presumably very old, very weak, and terminally ill to begin with.
If a person is young, strong, healthy, and weighs more than 100 lbs. they may want to up the dosage a little and take every precaution possible to reduce the risk of vomiting, and pain ( Metoclopramide, Tagamet, Benzo's , sleeping pills, and something for stomach pain)
The only failed attempts I've read about ALL got saved because of medical attention.
This seems to be the worse case scenario for a failed SN attempt
https://sanctioned-suicide.net/threads/sodium-nitrite-attempt.2902/
I recommend trying to obtain N if possible over this method.