"I also have a solid piece of Caapi at home, but never used it. Is there any major difference (in interaction, nausea etc.) between Caapi and Rue?"
I have done a lot of work with caapi and more recently much work with rue. Many people claim that caapi is nicer and easier to purge with etc..to be honest none of this is true IME. I love both caapi and rue but I never really found anything that puts caapi above rue for me. I think much of this could just be peoples self suggestion. I dunno, lately I have preferred to brew with rue and I just throw in a tiny bit of caapi as another admixture.
Try rue and then try caapi if you like. Might as well try them both.
Just dont eat the rue, then brew the caapi and then come and say rue makes you sicker
..brew the rue just as you would a caapi brew and filter it well, reduce and decant it. For me this makes a tea that is on par with traditional ayahuasca for sure.
Long live the unwoke.