Thanks Abraham!

I agree gamma is one of those things that people are so unaware of.
O.K. I have some cool stuff:

Previously I could only render HDR over the animation render farm which have me a (default sRGB) colorspace.

In the Animation Render option I ignore the fact it doesn't give you an option for '.EXR' and I pop the '.exr' extension at the end of the color channel file path.
This will render over the farm a Linear float '.exr' file.

To test it I'm dropping it directly into Nuke, the colorspace is (default linear. In Nukes 'viewerProcess' I flick between sRGB and None. When I view with (default linear) and (sRGB) it looks like it does in Vue. When I view (default linear) and (None) it comes up darker. I think this is what is meant to  happen?

Also when I render in Houndini/3Delight the gamma and color looks correct with my LUT.

So that is my process now.

Now I have to find a way to render a mulitpass cloud Mask in the animation render options :(