I dont think ive ever done opiates with a psychedelic but I can remember craving opiates after an acid trip once, I guess it could feel nice but I prefer being drug free after a trip, it seems to ensure I get the positive afterglow of the trip. Ive done benzo's after a trip and it just screwed up my memory and I didnt get the nice afterglow that only acid gives you(or me).
Never would I ever, ever do meth and a psychedelic, I think id go insane.
But yer, i use hard drugs on occasions(more often than psychedelics) and psych's are some of my fav drugs, I love my acid, mushies, 2C's and ketamine.
I have this feeling that taking opiates would take away alot of the challenges(If you could call them challenges) that acid presents to your mind, like I see acid as an adventure, something that has twists and turns, easy and sometimes challenging, but often the challenging parts end in revelations of things you never would have dreamt of, now without these challenges acid would only be colours and weird feelings...now colors and strange feelings are fun but I like the colours and crazy thoughts more and opiates tend to make me think about things a little less than usual.
I think if your gonna mix psychedelics with something it should be either MDMA/E or other psychedelics....coke, meth, heroin, benzo's, pain pills all that shit sounds like it'd be crap with psych's, save it for after the trip when you need a little relaxation...if you need relaxation while your actually on acid you must be 80 years old lol