Pregnenolone versus Progesterone?

Some of the stuff I’ve come across on here and other forums suggests that progesterone is a key hormone for adrenal function and the whole GABA circuit, but I also see pregnenolone mentioned more and more as something which could have similar benefits. Several guys on TRT at the musclechat forum are also supplementing preg. Anyone have any experience with either, or know the advantages or limits of one or the other?

This is a hormone chart from Rhein which indicates where each of them are situated in the whole picture:

rheinlabs.com/Rhien_Images/05_IL/05_SterPath.pdf