Right on, Gingerplum!
I'm just an EMT, so I'll bow to your RN experience and thank you for the follow up. As you are aware, I intend to ctb with eb/N2, so I am betting, confidently, that you are correct. And I'll add that my three flinches thus far have all given the same symptoms: tingling in my hands and a greying out of the edges of my vision. Not at all uncomfortable.
I suppose I'm not so much playing Devil's Advocate as anticipating more of the frightened comments that I've seen here of reported convulsions and agony with eb/ig asphyxiation. Are those reactions possible? I suppose they must be, and the list in that video includes some unpleasant effects, but I expect they're very rare and have more to do with inadequately addressing the risk of hypercapnic alarm then any response to the actual hypoxia.
I do hope my post did not imply I recommended against the technique, or thought it wouldn't be peaceful. I feel quite the opposite on both counts.