Rich, a 32 bit hdri (or float exr for that matter) should never need to be gamma corrected by the render engine. You should only have to tell nuke (I'm more familiar with fusion but I guess the tools are more or less the same) in what color space you rendered your sequence and nuke should be able to bring it in the right color space in your composition while preserving the full range of data.

The following paragraph only apply if your render without override appear washed out:

What might happen in your case is something a bit more annoying: all sky presets were created with the "old" work flow in mind and they all look wrong when rendered with gamma activated (I have a post about this on e-on forum) and even if it's relatively easy to bring the sky to the right color by applying an invert gamma to the color in the sky color slot, it doesn't work that well with the decay color

At the opposite, if you render appear way too dark in nuke, it's definitively something that need to be corrected in the compositing application itself (I suppose, you can in nuke, like in fusion, set the gamma of your input image in the image input node)

Don't hesitate to post again in this thread if it solves or not your problem, gamma isn't a subject interesting a lot of people, but it would be nice to create a good resource about it, considering how important it is for the final image :)

One thing I just thought about, you can easily change the default gamma output before rendering your sequence and bring it back to normal after that

• if too dark in nuke in vue you do Options -> Gamma options -> Output Gamma 2.2
• if washed out in nuke, in vue you do Options -> Gamma options -> Output Gamma 1

This should work fine on your sequence and get the job done, but I don't consider it to be the right way of doing it :). The right way should be Output Gamma 1 in vue and provide the information to nuke in the image loader node.