I have used 20mgs-120mgs of pure methylone. Only would I go past 80mgs would be when I was gaining a tolerance. I have a wonderful respect for Methylone, but my addiction to drugs drug me to a nasty place using it intravenously.
For one thing, it is a wrong assumption that IV Methylone would be any better than oral. I also have intravenously used MDMA, and I find it less pleasureable actually. There is no rush. I mean, it comes on quick, but for IV drug users, there is simply no rush.
With Methylone, it is the opposite. I can honestly say that at one point, and I still would today if I did not stop the abuse of it, that I like IV Methylone better than IV Cocaine or smoked Crack Cocaine. The rush reminds you of that, but with some warmth, a nice psychedelic and speedy rush.
Don't get me wrong. I do not consider simply IV use of Methylone to be abuse because it does provide a wonderful empathogenic experience for well over an hour, but it is quite easy to start a habit of using it habitually. With my knowledge of psychoactives, abusing Methylone would be very hazardous to your health.