Well, now I've had a little bit of experience, and can contribute to my own thread.
In short, yes there are similarities, but there are also remarkable differences.
With the dosages of caapi and psychotria I am currently using, ayahuasca seems almost indistinguishable from vaporized DMT, to me; although perhaps that is subject to change, if I were to drink heavier on the caapi. So, to me, the differences between 4-AcO-DMT and ayahuasca are analogous to the differences between 4-AcO-DMT and DMT itself.
The most striking difference to me is that 4-AcO-DMT is much more emotionally intense than DMT / ayahuasca. Which, for myself, I think is a bad thing, because I am a very emotional person as it stands, often to excess. So I think the fact that ayahuasca allows me to be a little more detached from my emotions, helps a lot to stabilize the trip and steer it in an intelligent and constructive direction. Hence, I much prefer ayahuasca. Although, I can easily see how 4-AcO-DMT's wild emotional charge could help me learn to deal with my own sober emotions, so maybe my opinion will change in the future?