I've just read through the entire thread and wanted to add my own anecdotal report, as someone in their late 20s who didnt experience mdma until the late 2000s, and so I'm not clouded by nostalgia for the "good old days" in any way. I don't have any chem knowledge so these are just my observations, trying my best to be objective.
I'm in Cali and have experience with MDMA powder from BC Canada, NL, took pills and powder in Berlin, as well as a fair amount of experience since 2009 with methylone, mephedrone, 4-fa, 6-apb, 5-mapb, and mescaline. I space out my MDMA rolls to a few times a year so I havent yet experienced "losing the magic" from fucked serotonin receptors, tolerance, or just becoming accustomed to the effects.
The mdma powder I got from BC was brown and smelled strongly of anise before I purified it using anhydrous acetone. It's now white powder and tests absolutely textbook for MDMA on 5 reagents and gives a relaible, incredibly blissful, euphoric, eyes rolling into the back of your head maybe even moaning and wanting to tell anyone around you about your childhood and how you love them, the things you're usually afraid to say, "this is how I wish I was all the time," lucid, horny, basically a perfect feeling at 125mg. The comedown is a comedown, but it's not dysphoric like a cathinone or high dose amp.. more like, oh I'm slowly losing that beautiful feeling I had before, but I still feel good. The next day afterglow is really nice like others have described. In some ways this reminds me of the day after 4-fa, where you still have some energy and general good vibes from the night before until late in the afternoon when you start to feel tired and the poor sleep from the night before catches up with you. With my dosage and responsible usage (only a few times a year and I do load up on the proper antioxidants) I actually don't experience a "suicide tuesday" or anything like it in the days following, but I think everyone's neurochemistry is different so this probably isn't universal even for good mdma. Also, pure mdma does drain serotonin so even with the best, racemic mix some more sensitive people are likely to experience a little depression after use - some might even have what they would describe as a "shitty" comedown on good mdma if they don't know how to calmly accept the gradual ascent to baseline, so I'm not sure this is the best subjective measure of purity or isomer ratio.
The mdma powder I got from NL was grey and didn't smell of safrole. Tested positive for mdma on my reagents. I didn't purify it so it requires a higher dose around 200mg or more. Mongy, people think it's MDA, low energy "couch lock," slightly psychedelic, not really good party material but still fun for a night at home. People aren't enthusiastic to try it again and would rather use K or even just plain speed at a party, which says a lot. Uncomfortable, with a body load getting closer to mescaline. I like psychedelics though so I don't mind, but this is definitely not one for the club. Really no dopamine pleasure to keep you positive out socializing.
The MDMA I had in berlin was fucking perfect, just like the BC MDMA. That was probably an outlier though since I got it from a drug nerd at an underground party. Set and setting do play a role in some ways (beautiful women around, a beautiful Berlin summer day, everyone feeling free), but you can't fake that dopamine and serotonin push. This is just to say that there is (or was, 6 years ago) good stuff in Eurpoe
5-MAPB with dex-amphetamine in the mix gives results very close to the BC pure MDMA (feels good as fuck), but none of the other research chems I've tried are anywhere close. So I don't think NL is pumping out cathinones or APBs because the difference is pretty damn obvious. 6-APB is like an intermediate of MDMA and mescaline. 5 + 6-apb in combo doesn't have the dopamine stimulation and clarity of mdma, and feels a bit more toxic on the body.
Not really related to the current conversation, but I agree with what someone said earlier in the thread and would like to repeat it: if any of you heads who love the empathy, lucidity, sexuality, and body high of mdma want to try something new, please do look into mescaline. You can buy peruvian torch directly from Peru, and just simmer it into a tea or if you want to minimize the disgusting taste and body load of the other alkaloids do a basic extraction (the instructions are easily found via google). The rolling, euphorc body high can rival MDMA, with a lovely psychedelic but lucid psychoanalytic headspace. The perfect drug for a night of therapy, either alone or with someone you love. Just a tip for those who have "lost" the mdma magic!