I grabbed the a plot of the iLIGO PSL frequency noise spectrum from the Rana manifesto:

Rana's contention is that this spectrum (red trace) is roughly the same as for our NPRO.

From the jenne/mevans/pepper/rana paper Active noise cancellation in a suspended interferometer I pulled a plot of the calibrated MC_L noise spectrum:

The green line on this plot is a rough estimate of where the above laser frequency noise would fall on this plot.  The conversion is:

    L / f  =  10 m / 2.8e14 Hz = 3.5e-14 m/Hz

which at 10 Hz is roughly 1.5e-11 m.  This puts the crossover somewhere between 1 and 10 Hz.