2) the perfectly nice trip that doesn't stack up to my one-before-last, universe tilting trip
I wouldn't worry too much about this. MDMA is still my overall favourite drug and go-to substance for a fun night out (although probably not again, for a while at least!), even though I know it'll never be as mind-blowing as it was when I was 21. What I mean is, I'm just glad I had those really wonderful early experiences, and I can still enjoy it getting on for 20 years later without it seeming disappointing or in any way a wash-out.