It would not be hard for someone to slap a cube in the scene with a few massive full float textures on it. My system does not have enough RAM nor a powerful enough GPU to work with that scene, though.
In the meantime, someone who tested it with and without HBCC enabled had significant RAM usage differences:
Well essentially no difference. Render time was 36:52.48 without HBCC enabled. Perhaps a larger sample is needed. I should note that Blender ate over 16GB of RAM vs the 9.5ish with HBCC, not sure if that was an anomaly or not.
EDIT: Does this scene crash a 4GB AMD card now? Does anyone have a RX 480 4GB to check? It wouldn’t take long to see if it crashes. Maybe AMD implemented some kind of HBCC feature in their driver for all newer cards.