ezlev: I don’t know whether they exist and it doesn’t bother me. There were great Gedolei Torah that held that they don’t exist. There were many more Gedolei Torah who held that they do. There are philosophical theological issues involved in believing in Gilgulim. There are other philosophical theological issues that Gilgulim can explain. At the end of the day, I don’t know and I’ll probably never know. I do disagree with your statement, though, that denying them is denying a part of our Torah.
HaLeiVi: The Ramban mentions several ideas from the Zohar because it’s clear that he had many of the traditions that R Moshe De Leon used when he put together the final text of the Zohar. And well-played with Heshel. But I think charlie meant a detail within Gilgulim, not whether or not they exist at all.