While I have the greatest respect and admiration for fastandbulbous, who is undoubtedly very knowledgeable about biochemistry and who is both a scholar and a gentleman, I am afraid that as regards "tan MDPV" he is COMPLETELY WRONG. I don't know what kind of "tan MDPV" he might have had, perhaps some inferior batch or other. All I know is this: in about august of 2009, I can into possession of a fine, tan-coloured powder, which I was told was MDPV. Upon vapourising and inhaling a tiny amount of this powder from a glass meth pipe, I almost instantly experienced the most intense and wonderful euphoria I have ever felt! Along with this came other feelings that I understand are typical of dopamine enhancing drugs; eg confidence, motivation, excitement, and incredible hypersexuality. Bear in mind that for a year or so I was a daily smoker of high-quality crystal methamphetamine, and no high I had ever had from methamphetamine was even close to that which I got from "tan MDPV" (yes for real!). Furthermore, there was no noticeable nervousness, anxiety, increased heart rate or shortness of breath.
In september 2009 I moved to the far east, so I left my stash of tan MDPV behind for safe keeping. After a month or two, I obtained some MDPV direct from a chemical manufacturer. At first I was surprised that it was a different colour (white) than the MDPV that I had before, but the smell was very similar so I assumed that it was the same substance. However, upon vapourising it the effects were TOTALLY different! This "white MDPV" produced no euphoria, no feelings of confidence or motivation, and no hypersexuality. It did however produce nervousness, anxiety, shortness of breath and a pounding heart, effects which I understand are typical of an oversupply of adrenaline. In short then, tan MDPV is a great deal of fun, whereas white MDPV is of absolutely no entertainment value whatsoever!
Given that my experience of these two substances was only a few months apart, and how clearly I can remember (to this very day even, about 18 months later) the effects of the "tan MDPV", I am ABSOLUTELY CERTAIN that their effects are very different, that "tan MDPV" is FAR SUPERIOR to white, and that it is NOT "just another drug rumor". So confident am I of this, I'd be willing to wager any sum of money (in a James Randi style challenge perhaps?) that the wonderful "tan MDPV" is not a myth! Hell, I even have still have some of it, unfortunately just not on the same continent as myself lol...