Hi,
To use the Render Layer technique, you need to enable the Alpha channel in Kernel settings, so the Main beauty pass is no more working as before, and you can see something like this:
But you can use the Output AOV Compositor in render Settings/OctaneRender tab to compose all the necessary AOVs and have the final result directly in Live View.
In this case, I have used the Environment AOV at the bottom.
Then the Render Layer Reflections AOV in Add mode.
Then the Render Layer Shadows AOV in Multiply mode.
And finally the Main Beauty on top in Normal mode.
Here is the example scene:
Happy GPU rendering!
ciao,
Beppe