I think this is a real Shadow Catcher problem this time

[treddie]

Yes. The one on the right has reflections that do not match the ones on the left. In that sense, inconsistent. It makes it impossible to do a beauty pass of just the subject without shadows and overlay it over the version with shadow catcher on, because the reflections won't be right in the top PShop layer. Which means you can't generate a mask from it while at the same time using it as the top layer. If you are going to need a mask of the subject for any reason, you will have to do a third pass in Octane to render a mask (totally black subject). You can't get two for the price of one, in that respect. So three Octane renders if not using a backplane image:
1. Render of just the background environment (1st pass)
2. Render of the subject w/ shadow catcher. (2nd pass)
3. Render of a totally black subject as a mask (3rd pass)

Why the mask? Because Octane has to use black as the shadow color which may not match the colors of shadows in the environment image. So you have to color correct the shadows, without affecting the subject. Hence, the mask image to be able to copy just the subject to the top-most layer.

[gordonrobb]

But the one on the right is right though I think. I think that one of the things that was fixed in a recent build was the matte material used to reflect just as it's default material (grey for example), then what they changed was that it actually reflects properly. Try it with a simple mirror on the ground and you'll see. Without a ground plane with the matte material, you are getting the wrong reflections I think.

[treddie]

Yes, the image on the right DOES have the correct reflections (as correct as they can ever be). By inconsistent, I mean they don't match the less accurate shadows on the left.