My own experiences thus far:

Huperzine: For me, a terrible, horrible, no-good-very-bad experience. First time use, I skimmed along in a dream within a dream. Kept waking up into (what I thought) was my bedroom, in my house, only to find that I was actually still asleep and dreaming. Then it looped. When I finally woke up "for real" it was to a state of confusion (am I really awake now?) and mental exhaustion.

Waited a couple of weeks, tried it again, same experience.