I'm having some issues with rendering hdr's in maya vs Octane standalone.
Rendering in maya with an hdr gives me a very bright scene with a dark hdr background

I saved out the scene as an Octane scene and render in standalone.
This shows a similar bright render with the background a fair bit lighter.

I then deleted the hdr node and reimported (all in standalone).
Both background and geometry are dark but now sit together.

Then I upped the power of the texture and all is fine.

The other issue in maya is that the Octane transform nodes seem to work in the Z only, which appear to distort the hdr as well as rotation.
cheers,
Steve