If i was to take methylone I believe that it would have a feeling similar to the empathetic and mood-blasting effects of mdma, but I don't think I would feel very speedy or "cracked out" like I probably would if I were to ingest mdma.
In fact, judging on the way it supposedly effects the body, one could probably fall asleep while under the influence of methylone if they really wanted to; it does not seem to have very powerful stimulant effects. I'd imagine there would still be some speedy feeling, though, but it'd likely be negligible compared to consuming mdma.
I've read from various sources that methylone has a great effect on a user's seretonin, which explains its likely empathetic effects, and has little effect on dopamine, which explains my theory that this drug when ingested would have little or not stimulant effect.
In theory mephedrone (4-methylmethcathinone, miaw miaw, and whatever other silly names it has gotten these days) mainly causes a dopamine rush in the user, similar but more powerful than mdma. This is why it has very speedy rushy effects on users as opposed to methylone having little or no dopamine rush hence its more relaxing effects than mdma or mephedrone.
It also explains why one user may find methylone to have amazing and powerful effects (not that anyone should ingest it), and another user may describe it as nothing special because they ingested methylone expecting it to be like mephedrone, and the dopamine rush isn't there with methylone, and so users seeking that "rush" would prefer mephedrone to methylone. A dopamine rush is the same thing one would experience with cocaine as well. This is why mephedrone is likely much more addictive than methylone.
My educated guess is that methylone is much safer and less harmful to the human body than mephedrone, when consumed in recreational dosages. If the FDA ever approves it for human consumption then I will definitely try the substance. I bet it would have almost no hangover/aftereffects.
Of course, these are all educated guesses of mine about the substances; I am not suggesting that I have consumed any aforementioned substances or that anyone should.