Hi Jesper,
Thank you for your anwser.
I get that samples in cpu and in gpu modes are not the same thing. What I`m saying is that in this case it looks like a bug, that engine cant smooth plain reflections even with high number of samples. I have this issue on almost every scene with glass and water materials. Also, I`m attaching another comparision of how it looks with 32 CPU samples and 1500 GPU samples. In this case scenario gpu looks just useless...
The fact that IOR looks different in this two image makes the whole thing worse. I know that I may look crazy, but there is a little difference in bottle color as well.
Yes, I know that such differences may occur, but on promo materials it looked way better. One click, and whole scene went way faster without such alterations... If this helps I`m attaching this scene.
I cant recreate this CPU rendering issue that I mentioned before. In this scene everything looks fine. The slow CPU rendering was only in rendering dialog. I suspect that this bug was quite simple. I set samples to 128 but in fact it was rendering way higher samples number - sorry, that I cant say more.