MDMA is more like a childlike wonder/intense sensory appreciation with its euphoria primarily being immersive in nature (depending on what music you are hearing, what are you are currently thinking and feeling, etc), while opioids produce more like a general feeling of wellbeing that spreads over the entire body and is relatively consistent, while also not having the general themes of immersion enhancement. Comparing the two is a lot like comparing coke and weed, theyre not really the same class at all. In terms of memorable experiences, MDMA takes the cake for me. I would just try it, there's no real comparison that can be made between it an opioids