Yes, it supports HDMI 2.0b.
No, it's not gold-plated.
To be fair, none of the HDMI extenders that have come with any of the different streaming devices I own is gold-plated.
That all being said, one of my three (1/3) Roku-provided extenders is flaky/dysfunctional.
All were "free" of course (including those that came with competitors products).