Well, apparently pregnenolone (at least taken orally) will convert around 50% to progesterone, so maybe the antiandrogenic results some people is seeing with pregnenolone (discussion here) is not only because of the progesterone conversion but also because of the progesterone conversion to allopreg and then causing GnRH inhibition. I'm starting to suspect that these kind of problems do not depend that much about the dose "per se" but depend on a ratio, like if you have a good endogenous production of androgens (or taking them exogenously) to oppose all that antiandrogenic activity.
I agree, and that is why I think it is important to add DHEA or another androgen to pregnenolone/progesterone. Pregnenolone actually may be OK as in lower doses it does seem to favor both the DHEA and the proegsterone route and only in higher doses does it become predominantly progesteronic. But if only progesterone is taken then I would definitely add DHEA and ideally DHT.