So, I'm on the return leg of my road trip. I tested the ARNC yesterday after the 2021.44.6 update and now I do actually hear a difference. It's small, but it's there. What I can't tell you is if there has actually been a change to the ARNC due to this update, because the road I tested on before (with 44.5) was freshly paved. The road where I heard the difference produced a low rumble in the tires, such as something like rumble strips, and I believe that low-frequency noise is right in ANC's wheel house.
When I flipped the switch, the rumble was reduced a bit. It's a start, but nothing to write home about. I guess it just stays on, and we hope there isn't a bug introduced that amplifies the noise instead of reducing it...