I found the same thing in my tests here. I ended up using HFI gain set to 0.100 and it solved that issue completely (trampa hardware, and stormcore 60d+). The stormcore made an audible whine when using sHFI, and the trampa esc was nearly silent other than a loud click when sHFI engaged.
I’m considering using the BioX for my next 4wd build to avoid using sensors and sensor extensions.
What did you find the noise like on the BioX when using sHFI?