Ah, I see. I didn’t know you were utilizing IPP2 already. 
I’m not that familliar with r3d’s and Nuke. But I wonder though if there is a way to skip exporting to exr to make data much more efficient.
As what colorspace and gamma do you export your R3Ds to exr?
I also wonder if there’s loss in data if you’d export in rec709/linear in order to presumably include the IPP2 tonemapping over directly converting the full RedLog3G10/RedWideGamut to ACEScg as working space.
I should do some testing on my own to get a better understanding on that too actually!