IIRC when MacMillan designed the (I think A5) stock for a military contract they took a bunch of shooters, including .mil snipers, and had them mime various shooting positions and measured and averaged the natural angle they held the wrist and the corresponding angle on the pistol grip to support those grip angles.
Other that I do not have anything else to add as I have not tried them, and don't know if I will. I am happy with my old skewl Tango Down AR grip I got from Uncle Pat.
pat