geez: as an IV user, I appreciate the "rush" my good gear gives me, but whilst I call it a rush, I'm pretty certain that its the same this as what your talking about.
Having used Hypo, Phos and RP all of varying quality with LG I2 (and progressivly more and more h20-funny about that)in rxn's ranging from 3-20 hours for a couple of years now I'm pretty sure I've got a idea of the "awareness" you talk about.
However, its my experience that there is a "saturation point" for your body. If I've had a couple of clean days, put a cook on, sleep for 15 hours (big meal etc etc) wake up, work it up, bang it up, it takes 30 to 60 seconds to start to feel the "thump" (i usually use 0.125g) it can be like you say, a sudden feeling (angsity) that the elevator aint gonna stop at your floor. Then its bright eyed bushy tailed for quiet some time.
However, here is were there maybe some confusing for some bees I beelieve.
My body wasn't saturated for this first one, and me being an absolutly disgusting pig every once in a while, will follow this 0.125g with another an hour later, and maybe one more a couple of hours later. and with the first "dose" saturating my system, these next two have a somewhat different "thump", you can feel it whilst its still in your arm, its dazzling (and damaging), but yes you could call it a "rush", i can't usually call it anything for a couple of hours, but thats the general idea ;-)
I once hit .31g of some very clear glass beads after an error with my slide bar scales (the zeroing weight was well out) and I can say for certain that that was an absoult "rush", but only because that elevator just didn't stop. I realized something was wrong when jacking back and my blood was an extraordinary crimson, but it wasn't dispersing in the water, it had a very sharp edge to it- i was pushing it in at this stage and as I got near the end I work out that what all these things were caused by was the incredible thickness of the liquid, but it was toooooo late.
Yes that was a rush, but I know it wasn't solvent, or salt for that matter.
Yes, I know these ammounts might sugest to some that I don't know what "cooked" means, but whist i'm sure its not as good geez's or other beez i know it anit that far short.
Sorry for the ramble, but i understand the "if he gets a rush, he doesn't get it full stop" point of view, but also feel that it may just be the way an individual describes it.and lets face it, whilst you feel like your thinking with world class clarity, your observations ARE under an influence not matter how good your shit is.
He say rush, I say don't be rash. It might be the same thing.
and thats my 2 cents worth.