Last night, I left the two ISIs at the corner station with the aggressive feedback isolation filters and the feedfoward engaged. HEPIs are just controlled in position (100mHz UGF). Configurations were almost identical (cf item 5) on both ISI (low blend on translations and high blend on rotations to limit noise injection).

I have attached spectra of the stage 2 motion in the Y direction.
Note that:
1- ISIs didn't trip during a long stretch of time. The control is very robust (the ITMY feedback filters were even designed with the HEPI locked)
2- The stage 2 motion in the Y direction meet the requirements for both ISIs
3- The performance are similar for both ISIs
4- The feedforward control allows squashing the HEPI pier resonance on ITMY (feedforward filters clearly need to be reworked on BS)
5- ITMY performs slightly better than BS at low frequency. I noticed that the sensor correction was engaged on stage 2 in the Y direction. It might explain the difference