"HDRI on bill's envsphere allows more realistic rendering than ordinary scene with default poser lites.  it's the most advanced implementation of IBL in poser yet provided."

I know it was a couple days earlier than the reality 3.1 release; but, R3.1's integration with sIBL is probably the most advanced implementation(and easiest) of ibl in poser.  I've not had the opportunity to use octane's ibl; but, I use ibl in nearly every render I create and R3.1's is the easiest and nicest looking(for me) to date.