when I had sex on 5-meo-mipt, it felt like I was constantly on the verge of orgasm, but simultaneously felt like achieving orgasm was a lot more difficult than usual - which was amazing. We fucked for like an hour and it felt like that. And there was definitely some synasthesia - the genital sensation were turning into pleasant blue fractals that I could see in my minds eyes, and there was a nice auditory buzzing component that was nice.
we tried to use it two days in a row, but on day 2 it gave the girl friend diarrhea, which was decidedly unsexy.