So we ran overnight at ETMY with the HEPI position loops on.  I've revisited the data I posted yesterday morning.  In the attached plot I've added some of last night's overnight running with the loops on.  The dashed lines continue to be the off loop reference from ~2AM Tuesday, The solid line references(REF17+) are with the loops on but starting about 8am Tuesday, possibly a noisier time.  The current traces are from 2AM Wednesday with the loops on.  It is involved but my simple analysis says that some places are worse with it on and at another time it is better suggesting it is just dependent on the ground motion at the time.

When I started the loops yesterday I just put the current positions into the Target. From my log I put in 12 March, the Target positions should zero.  The differences are 57 to 30 ums in position,  11urads tilt, and <7 urads Rz.  The HEPI Position at ETMY is ready for controlling as needed; so if the current position is not close enough, go for it.