^I agree with ya'll as well. I always chalked up PPT's longevity as well as it's pleasantly unique buzz to the whole lot of other alkaloids present, kind of like what you mentioned, kratomluver.
I think that when a solution such as a "tea" is made and ingested, you are taking in the whole slew of psychotropic alkaloids, all of which react differently in metabolization, and have different psycological effects. For instance, the morphine utilized from pod tea may not all be taken in at once,(sort of like a natural MScontin, yes^) but over a more gradual period of time, due to the inconsistencies of the tea itself, and the presence of everything else; active/inactive alkaloids, plant resins/plant material, etc.
Also, you never know exactly what to expect from pod tea; for instance, 200mg of morphine sulphate will more or less produce the same effect each time(not considering tolerance). However, a tea made from the same number of pods can vary greatly from batch to batch, and subsequently makes it more difficult to determine what to expect.