Just skimmed most of these posts, but wanted to offer my insight, as I'm rather experienced with pure MDMA hcl.
The only MDMA I have consumed in the past year and a half has been pure MDMA hcl - we're talking bricks of crystals that always include a material safety data sheet (
http://en.wikipedia.org/wiki/Material_safety_data_sheet). In the past year and a half, the purity has ranged from 94-96%. The remaining 4-6% are impurities - chemicals and solvents that have not been washed completely, or somewhat impure residue left behind from previous batches.
94 or 96%, I still always roll ankles as long as my tolerance isn't through the roof. The psychological effects of both batches are nearly identical, and I find similar levels of euphoria and empathy. I will say, however, that depending on the purity and the wash, minor differences in physical effects have been noted. Usually the stuff closer to 94% is more off-white in color, and generally has more of a body high/load than the 96% batches, which are usually much whiter/clear in color. (the higher % batches also seem to be more opaque and have better physical structure; less crumbly and chalky, etc.)
Some of my less-informed friends would like to attribute this body load/couch-lock effect and off-white color to a more "MDA-heavy" batch, but this is wholly untrue. The off-white (sometimes even brownish) color results from the remaining, unwashed impurities - not from MDA. Although I am not entirely certain, I believe that the "stoney" effects of these batches is also related to the impurities - especially since the stoney feelings from these batches are unique to the stoney, couch-lock effects of MDA, which I am also quite experienced with.
Anyways, I wish this could be the standard for MDMA across the world...it's a very special gift when it's not adulterated to hell. I've had so many first time moon-rockers tell me they've never experienced anything comparable, even in the hundreds of pills they've gobbled down over the years.
Keep looking, it's out there.
Be safe, stay healthy.
edit:
I would also like to add that I've only ever seen one batch of 84% MDMA hcl. It was procured by a friend of mine, from a different source than I usually procure mine. The crystals were very small and every one took on the shape of a grain of rice. I personally did not consume this batch, but my friends who did said it was certainly MDMA, but not as strong as the 94%+ batches we've had in the past. A test kit identified small amounts of lidocaine (an anesthetic), and consumption numbed the mouth and throat. The strangest part of this whole shabang, to me, was that every crystal was the exact same size and shape. I'm not entirely certain what that's indicative of, other than that it was produced differently than most of the MDMA hcl I've had, or that it was adulterated after the production process.
