If I may drop back a little (well, I'm going to anyhow)

"....at least those who were REALLY floating above the operating table KNOW what they're talking about!"

Yes, they know what they're talking about; they are talking about an experience in which it honestly seemed to them that they were floating up there. Neither of us is a know-allogist about it. You don't know for a fact that they were floating up there, and I don't know for a fact that they weren't.