Dex VI is backwards compatible with Dex III, II, IIE, etc., so yes, it should be.
I suppose the question becomes what shearing characteristics are in a PS system vs. an AT. Dex VI has a better base fluid and is far more shear stable, but it starts (and ends) at a lower viscosity.
Id venture to guess that it is no different than using M1 ATF as a PSF, which many (myself included) have done for years.