Big Navi will have HBM2E. AMD codeveloped it to use it on their high end parts. Its not as expensive as it was. The tech has matured and it is a better solution vs 4 - 8 GDDR6 chips throwing heat all over the place.
You really need to get your hands on a Radeon VII. Freesync or Gsync make the fastest card in gaming kind of a moot point. its compute speed and memory size for the price is where its at.
Navi for the price is great as well.
The fix for navi seems to be 19.10.2 drivers. Its likely that new features and overlay is fucking things up for some. its also a good idea to reinstall all the drivers after windows updates. Install radeon drivers last.on new builds and fresh windows installs.