By the time its getting to the stage that you are feeling physically floored i would expect it to feel like my brain is literally flooded with seratonin, all i am capable of doing is sit there google eyed talking shit in a rose tinted haze. Yes we are talking taking to much, maybe 300mgs plus at this stage of a session, but you would be physically rushing pretty damn hard imo by then. It doesnt happen often enough even when you take more than you no you should be taking.
As for crystal the only time ive taken what i consider to be quality MD crystal it has been clear, maybe coincidence but thats the way its panned out for me. Grinds down to a brown powder and it doesnt seem to break into small pieces, pieces tend to be quite robust and chunky, but there you go, probally coincidence...
White MD crystal ive taken has been the poorest feeling overall in quality, as you say ive had white MD that just makes u feel a bit heavy and that is literally it, no empathy at all, again probally coincidence...