I was clearing out my hard-drive when I found a word pad document with 4MEC notes on it from August 2011. I will just summarize it.
My first time using it gave me similar effects to mephedrone, say 65-70% 4mmc, and alot shorter duration. Redosing worked to an extent and after that it made me feel nauseated and almost poisoned.
Report 1
There was the initial 'crazy rush' feeling where you think 'oh here we go', it was stimulating with that 1000mph feel, I had a huge grin on my face from ear to ear and my sense of well-being was through the roof. Slowly I got small waves of orgasmic pleasure passing through my body, lasting maybe 1-2 seconds, coming every 20-30 seconds, each orgasmic wave lasted longer and longer until it was pure bliss, it was the feeling of one long orgasm, I would close my eyes and gasp at the sheer pleasure. This then slowly faded off and I was left with music appreciation, a high ego and endless horn, maybe 75% of the 4mmc horn. A redose repeated the effects, but the orgasmic waves were half the strength.
Report 2
So it was 2 weeks since the above report, I took my dosage and experienced all of the above effects but the orgasmic pleasure part was maybe 50% or less of the first time. When I re dosed this time it turn me into a sloppy, mentally confused mess, like I had been drugged with a downer and I found it extremely hard to concentrate, it was a really unpleasurable place to be in and I found myself at times closing my eyes and almost 'blacking out' - I would snap back into reality and 30 minutes would have past. Not nice at all.
Report 3
6 Months after the above report, I was in a group of 5 at a party and 4-MEC was the intended chem for the night. I was the only occasional 'light user', the rest of the group were moderate street drug users. I experienced the same great effects as stated in report 1, with redosing effective with 50% of the orgasmic pleasure.
The other 4 in the group didn't respond well at all, they pretty much immediately got very sloppy, and in a confused mongy headspace. I was actually quite concerned due to the appearance of them all looking very fucked and sleepy but they didn't seem bothered and just kept on saying 'oh this stuff gets you messed up, what the hell is it, its crazy' I made sure they didn't re-dose, I was really concerned, and it took them a good 2-3 hours to come out of this state.
Hope this helps.