I think That ayahuasca has less nausea than hbwr (esp. 20 seeds) .

There are many factors determining the nausea with ayahuasca ( Type of admixture beeing one of  the biggest).

The duration depends one the dosage (the nausea also) . I am sure that you can have an ayahuasca experience beeing way more gentle than your hbwr experiences.

Oh, and if you like hbwr, try the defat ( i guess its called panoramix Tek in the wiki). Its amazing !