I think allot of this has to do with dosage and release rate of the mdma into your system.
I've always suspected apart from obvious quality issues surrounding illegal drugs, that allot of folks simply do not dose right with mdma due to lack of knowledge and lack of sensitive enough scales.
mdma effect varies greatly due to initial doseage and how quickly it absorbs into your system.
Shulgin always reccomended a max 125mg dose. Now in a good pill which has the right dose and the mdma breaks down slowly as well as maybe a hint of caffine can make a big change in how the come up feeling is.
I know so many people don't get the right effect of pure mdma because they either do too much and mong out. Or dab too little and never get the nice come up.
Sudafed capsules 300mg have a good release, and if you half fill the large side of the capsule with well crushed crystal you should have something in the region of 125mg
;-)