How is your experience with the inerter? Did you see any effects in some track conditions (i.e. bumpy)? Did you tune the mass or leverage to work on it? I remember Schumacher had a #tuned mass damper# in the Mi8, but it never really came to be a thing. I myself had to tune a mass damper for bobsleigh once, and the effect there was negligible - and rather strange for the pilots.
The most important gain is that I can use stiffer springs. The Inerter will make the car softer only when I input fast steering changes, or high speed bumps. The efficiency of the Inerter is its Inertance, wich in this case it is 10 times bigger that what you receive from a tuned mass damper. On my first prototype from 2013 I had 28g weights and an inertance of 250g. Now I manage to put 42g with an inertance of 600g, This gain is from the ratio of the rocker arm and fine tuning of the parts of the suspension. The bigger the inertance, the more you will feel you can make the springs stiffer.