Swim's had a hard time getting caapi to work right. Might be his brewing technique, though he's had some practice... if your 25g isn't powdered, and you don't brew it at least 3x, at a full rolling boil, for 4 hrs each time, I don't really see 25g doing the trick. That all depends on the strength of the vine too though... if you got really kickass caapi, 25g might work, but "regular" strength seems to require at least 50g based on general concensus from the aya.com forum, and Swim has found himself brewing as much as 1/2lb caapi per person to ensure effectiveness.
As for mimosa, Swim has had horrible luck brewing it as a tea. His first two attempts failed, and his third succeeded but only cuz he used egg white to remove the excess tannins (he barfed up the first two rather promptly after chugging). Even then, he had to drink 46 grams worth, in four separate brews of 11.5g, adding more harmaloid extract each time (failure of the first brew or two may have been due to insufficient enzyme inhibition, as Swim didn't really know what he was doing back then
). He then proceeded to trip hard-core balls.
It's true that, esp. for first time, you're better off brewing at home. I hear you on wanting to cowboy it, that'd be great, but I fear you may be underestimating everything involved in making a brew.
For the closest thing to an ayahuasca experience that you can find without being a brewmaster and spending hella money on caapi or a plane ticket to the jungle, Swim recommends his pharmahuasca tek. Using limonene to extract from mimosa, and facilitating it with harmaloid freebase extract, brings such amazing healing medicine into your life that there's really no way to describe it. And rue and mimosa are cheap enough that Swim has been able to provide ceremonies free of charge for all who would desire such. Caapi is a great spirit, but she is touchy, and seems weaker away from her source of power in the jungle. Rue, on the other hand is a desert plant, as is Mimosa (Swim considers himself a desert spirit), and both give plentifully. As with any plant, one must simply learn the proper method of approaching them in order to unlock their healing magick. Swim believes he has found this method... his tek is still on the old forum archives right now, but he will move it to the new forum, and post a link here when he does, if'n you're interested.