How significant is the difference in quality and potency between say a caapi+mimosa brew, and a brew made from caapi + whatever freebase dmt was extracted from that same amount of mimosa......is it running the mhrb through an extraction to end up with freebase to dissolve into the caapi to avoid the mimosa's taste?

An extraction is made to avoid nausea, provide a clearer trip and to accurately DOSE how much DMT is in it.

Alkaloids can vary depending on what the source of DMT is. Some acacias contain contain less than 1% and therefore lead to less powerful trips and being underwhelmed. Some people have reported yields of over 2% with MHRB and thereby become overpowered. That is why people prefer to extract it. And in reality, an extraction really isn't that complicated to do.

Will nausea be avoided if the extracted freebase is mixed into a caapi brew and downed?