Sananga is a super potent energetic panacea when it comes right down to it.  The vision part is just one attribute, honestly it has entheogenic effects similar to Iboga but much lighter on the whole system.  Yet you can feel that sharp Iboga like focus as it is coming from Tabernaemontana Sananho a close relative of Tabernanthe Iboga.  You got Becchete' right it comes from Tabernaemontana Undulata, this one is more feminine and gentle. 

What plantbuddhist described was the Sananga that I made previously, unless someone else other than me and the Acre tribes are making Sananga.  I made it not as strong but now seeing how freaking potent the Yawanawa make it I know how to make it better to be extra potent and still safe.  The previous kind I had was made by the Huni Kuin and wasn't as strong so I had used that as the bar. 

I apologize as I can't fulfill the request currently to give coherent and broad ranging information about Sananga and Rape' varieties yet.  I feel they deserve dietas of 2 weeks each before thoroughly evaluating.  I could give my thoughts on the 7 or 8 varieties I have tried, but it wouldn't do it justice quite yet.  I remember one Brazilian Rape' connossoir that made a blog describing his experience with many varieties.  Maybe you could find as I'm not sure how I found it or if I can find again.