Maybe the +4 is rare 'cause very little people have the courage to actually take a high enough dose to experience this.
But I think from the description that you can pretty much tell what kind of trip you had. I mean +3 experiences can still be heavy, but still not be a +4.
I think +4 is the stage where you go deeper into the rabbit whole and are more in you subconsciousness and going to other dimensions then tripping your ass off in the "normal" reality
But I deffinately agree that those first three stages, can be really weak and +4 suddenly is absolute bliss.
I've had situations with mushrooms and acid, where I was still fully conscious of my surroundings, but couldn't deny the stuff was fully at work and I was tripping quite hard. Still it was a +3...
Maybe with the
Psychedelic Information Theory we can form a new rating scale, 'cause I've read the part of
the Metabolic Tripping Curve in Detail and this deffinately has a really good description of the stages you encounter and I think this is a much better understanding of how heavy a trip was (if you've been to the peak or just the plateau) then the Shulgin ratingscale...
I actually have the idea that everytime I'm at +1 or +2 I'm not having a good time 'cause I'm somewhere in between worlds and for me that's a bad place to be.
And the reason why I didn't react to the poll is the answers are clearly based on 1 opinion and I don't think Shulgin's rating scale will do anything for humankind, maybe just give a kind of ratingscale for trippers.
I think you can only use the ratingscale to tell when you had a +4.
I had 2 +4's on DMT, that's for shure
Went pretty far on LSD and Shrooms (not as far as HC though...), but still haven't had a +4 on those...