Are they quantifiable? Are there notable prerequisites and repeatable metrics?

They're incapable of testability. Nothing about them is potential of science - actual knowledge - and they are only anecdotes. Inform me when you can set up experiments to test whatever theories you have about NDE's, and I'll carefully examine your proposals for evidence of bias. I'll be very happy to find none, and carefully consider any reproducible evidence.

LOL Who are we kidding? That will never, ever happen, because some girls will dance around with crystals on a full moon and that will be PROOF that Satan is God, or smth.