Hey All,
So after quite a lengthy delay, I finally had my car into the shop and it's back now.
unfortunately, the lower gear assembly DID NOT resolve the hiss. I feel bad for the dealer. They had my car in for 72 hours, they had to drop the entire battery and motor assemble to install the new lower gear drive. After all that work there is no noticeable change to the pitch/volume of the hiss. It's still very much noticeable.
I'm not sure how the lower gear assembly solved the hiss in that Kona in the UK. The sound they posted was absolutely identical to mine.
Unfortunately, the dealer believes it's just a poor engineering decision and there's not much more they can do until it's officially acknowledged by Hyundai. I honestly can't blame them at all. At this point - I essentially have a brand new car and am in the same position.
So it's Hyundai's move! If the 2020 model solves this issue. I will go to the better business bureau or get a lawyer involved to have my car replaced with a new one.