Seems like i picked a good thread to jump in on.
Hello everybody :D After being introduced to 4-MMC a few months ago i decided to start looking into it. Have i tried it? Yes. Was it fun? Yes. Did i have any negative side effects that would cause me personally to stop taking it? No
That being said i normally do quite a bit of homework before trying something new. In this case I didn't and shame on me for it. :/
I have noticed the bluing reaction occur in some people's lips, but nothing beyond that in my circle of acquaintances has been brought to my attention. My initial use started off with an oral dose of approximately 250mg and was followed up with 2 or 3 bumps. I found it fun, but it seemed like too much in the sense that i felt i could achieve the same with less. So over the course of the last few months i have scaled back and found that i have very nice results with an initial dose of around 100-125 mg insufflated with additional doses every 2.5-3 hours. Normally the follow up doses are also snorted and are between 50-75 mg.
Although several people had reported having negative effects when combined with cannabis i found that to be entirely opposite of what i and several others have experienced. Cannabis actually made it a tad more empathogenic and added a very nice, but mild euphoria to things.
There is some anorexia the next day, but by day two afterwards it's gone. I have not noticed any troubling aftereffects, but i also have not used more than maybe 400 mg in once session. Water intake is important as is making sure to eat well prior to ingestion. As i feel that it causes more than usual potassium and calcium depletion (can't tell why, but it's a hunch) i also have recommended milk/calcium intake before and during and some standards like bananas and citrus fruit.
I am in moderately good health. No smoking, no drinking, some cannabis use, occasional use of other entheogens or recreational drugs. Lots of exercise from a variety of sources, lots of organic whole foods, and fresh air. The only persistent side effect for me has been the anorexia and that really doesn't last more than one or two days at most. Otherwise I have a generally elevated mood and energy levels for at least several days afterwards.
My sleep is only a bit difficult immediately afterwards, but even then after one good night of sleep it's back to normal. While i don't get "the blues"/depression from MDMA i find the next day can leave me feeling more physically and mentally tired. This is much milder, if present at all, with 4-MMC. In general i don't seem to suffer ill effects from stimulants, so take it for what it is worth.
It does have hyperthermic effects on me, but about on par with MDMA, although i sweat a little bit more on it when i do get into sweating. Tactile sensations are very present and very fun, but it is less emphathogenic than MDMA. On the other hand it does seem to be a potent aphrodisiac for some and i am one of them.

I find it easy to communicate on and I am a bit more talkative from feedback, but that's only noticeable to people who know me very well.
Sorry for the rambling.. it just occurred to me that this is a good case study to demonstrate how wide a range of reactions people can get to the same compound. I was noticing while reading through the thread that several of the individuals that reported having generally more negative reactions to the 4-MMC also seemed, from my observations, to respond to stimulants in ways that I do not.
Maybe there is a case to be made for genetic compatibility/susceptibility with this drug? As with all drugs. Being "only" anecdotal i can recall from personal experience that cocaine, for example, will allow me to be a very attentive listener and very calm. Not the response many people get from it.
I am glad that some warnings have been posted about the drug though as we should all do our best to stay educated about these things. Some of the amounts that people have been using flabbergast me though. 3,10,20+ gram binges or frequent use? The only drug i would consider taking in those amounts is cannabis. Even with researched drugs i wouldn't ingest amounts that some people have.
thanks to all the contributors. I actually did read the first 25 pages.

With all the additional information in hand i will also advise people of potential risks and rewards of doing this still very new drug.