As of now, my method of choice is still inert gas (nitrogen), but after pondering all the mentioned methods in this board and reading scientific literature, I came to the conclusion that all off these methods come with a degree of violence. Killing a human being simply isn't easy. This is a fact all of us that want to cbt have to come to terms with. This too is true for nitrogen. Passing out from nitrogen is accompanied "on most occasions by a generalized convulsion" [
1], you don't just fall asleep.
The question if there is an amount of pain is hard to answer because nobody who ctb'd can talk about what they experienced in the moments until their death. Obviously you can't just do experiments on humans. As far as I know there are just two papers where the process of ctb'ing with inert gas - in both cases helium - was scienfically obversed, the researcher in both cases was Ogden. In one paper he watched videos that were taken by the Swiss organisation Dignitas using oxygen masks, in the other paper he was present when two elderly women used the exit bag. In both papers the observations are described, I'll attach them so you can read for yourself. It is not for the faint of the heart. One paper also contains pictures of the deceased. Concerning pain, Ogden writes:
"While there was no evidence that the decedents experienced any pain, it was disturbing to witness preterminal gasping in both cases. In adults, gasping is witnessed in 30% to 40% of cardiac arrests. These 2 case reports are insufficient to determine any variability in human response to helium induced hypoxemia, but it is interesting that one decedent experienced no tremors or gross reflex, while the other one did. In an experiment using nitrogen for the euthanasia of dogs it was observed that while death in the canines occurred rapidly and humanely, there was also considerable variation in incidences of convulsion, gasping, and muscular tremor. The underlying reasons for these variations should be explored"