I don't think there's anything about SN in particular that would preclude someone from remembering everything up until the point of no consciousness, nothing sticks out as making it more likely to cause amnesia than any other method before LOC. Of course, some people get some form of amnesia in an insult to the brain, but not always. In my non-SN attempt nothing seemed verifiably missing even after a coma of more than 2 weeks and anoxic brain injury.