Using 2015SP2. I'm getting color corrected render regions when "Apply to render region" in color management is on and a profile curve is set. I think this is expected behavior.
The only issue I'm getting is that the octane output seems to be a 8 bit/LDR image and shows banding when color management is applied in XSI.
When the XSI color managment is OFF (profile curve set to "no LUT"), then the output is the same as octane standalone which is a good solution and I can use Octane's color management with the imager node.
There's nothing wrong with the plugin (in fact it's great!) but what would be nice is if there were an option to use XSI's color correction too (It's so fast and nice to use with the sliders and all