this is a confusing thread...Whenever one is making a thread, I think its important to question: Am I making the thread clear? and also, is making a new thread for this necessary, or can I ask (or find the answer to) the question elsewhere?
In any case, you posted in the changa subforum, so I suppose you want to make changa? If so, then its caapi leaf you should go for. Caapi vine will work but it doesnt taste good, its not really recommended for making the base of changa.
But then you say "MAOI and DMT" seems crazy. What do you mean by crazy? And are you talking about changa or are you talking about oral ingestion (because thats what you just mentioned in the sentence before). If you want for oral use, then go for caapi vine.
About 'trying a little', are you talking about oral use or changa? If its for changa, dosage should be more or less the same, maybe a bit less, than what you normally need for dmt (so equivalent of 30-50mg dmt would be a full dose, or 60-100mg 1:1 changa). Personally I find it unnecessary to weigh when smoking, I just load up and smoke till I physically cant anymore, when I want a breakthrough. If you want to just get the taste, you can just take one small hit and see how it feels, then take a larger hit later if you feel you can go further, and then a couple of hits, and so on.