fairnymph, at the link i posted he actually describes the effects at different doses of the racemate and both the d- and l- isomers (he refers to them by their "S" and "R" labels, respectively; remember they're reversed)
look above.. he says that d-MDMA "lacks the fire of the racemate"... pure d-MDMA would definitely be better than pure l-MDMA, but evidently the racemate is the best way to go. there's probably some perfect blend; no idea what it would be.
since you always end up with a racemate, if you separate the d- isomer because it's 'more potent', all you end up doing is throwing the l- isomer away, even though it *does something*. i mean, look at his descriptions... even at very low doses, with the racemate he's always amazed, blown away, classical MDMA experiences. with the pure enantiomers he's more like "Some jaw clenching, no nystagmus." that's from 120 mg of the d- isomer; if you assume, incorrectly, that the l- isomer does nothing, that would be equivalent to 240 mg of racemic mdma, and he doesn't even *try* that much (he's not a raver, yknow).
it's quite possible that the receptor binding profiles of the enantiomers are very different, and somehow the full experience only occurs if both isomers are present (like two drugs in one...). there are many 5HT receptor types, and shulgin points out that the fact that MDMA and MDA are not cross-tolerant suggests THEY work at different receptors, so why not the enantiomers too?
ronald: i'm not sure about clandestine LSD, but wasn't sandoz's Delysid enantiomerically pure d-lysergic acid diethylamide tartrate? when they made acid illegal, everyone apparently said that delysid was way better or at least subtly different because it was 'natural'... maybe it was the stereochemistry?
as for your last part... the stereospecificity of enzymes almost makes me surprised that the whole concept of a drug is even possible. but it's not the enzyme that *makes* it d-meth... you're still working with a compound that's already '2S-N-methylamino'. the two starting materials are chiral at their 1-carbon too. the product is not. the synthesis eliminates a chiral center and produces d-meth in all cases.