A friend and coworker of mine (pilot) wrote his masters thesis on this subject, I’ll see if he can supply a link to his paper.
As part of his research he measured the vibration levels at the pilot seat on every test flight his crew flew using a Chadwick 8500 and the assistance of his crew chief(who also happened to train me on vibration analysis/rotor tuning when I first entered our Test Flight section).
He compiled quite a number of the Chadwick printouts before all was said and done to document his work. As much as I like IVHUMS I sometimes miss the 8500, it just worked, unlike the crapshoot you had with AVA.