You're asking questions nobody really can answer because the substance hasn't been studied enough. 20 grams is the often said sweet-spot for most people. Those taking huge amounts daily tend to stop at 20 grams per each sitting. I don't think anyone does benefit from higher than that. On adderall I can ingest more than my usual dose (capped at 10 grams per sitting at most) and not notice the negative side effects.. but I think it's purely subjective and the interactions of other substances are not really chemicals at play just how one is processing different effects of substances simultaneously. On benzos you'd be able to take more without worrying about dysphoria and I do find it to be more euphoric, but only because the benzos seem to blur out the negative side effects of it. I might just be babbling and way off your question lol.
Btw I've seen information floating around that the USA is attempting to ban it still. I can't confirm any of this but once again I am wildly disappointed at my government's attempt to save people from their poisonous epidemic. Suddenly thousands will be wicked sick from the kratom ban and forced onto stronger and cheaper things like fent-laced heroin

I don't know how much more time there is for it to be studied :/