Quote -
NOTE: I'd suggest not selecting gamma correction in the Poser Render. Gamma correction is included in the above 32-bit editing workflow above and you have more control and instant feedback in PS.

I suggest the exact opposite.
Poser Pro always saves linear data to linear file formats - it never gamma corrects what it writes to OpenEXR and HDR, just as those file formats are specified. However, in order to get correct linear data, the input textures need to be converted to a linear color space too. That conversion is what you get when you enable "gamma correction" in the render settings.

Imagine the checkbox wouldn't read "gamma" but "linear rendering", since that's in essence what you get then.