I roughly calibrated an IMC spectrum taken during one of our longer high power locks into frequency noise.  
This spectrum was taken with high CARM gain at 23 watts of input power.  It was taken at IMC Servo Board Test1.

Well informed guesses about the laser frequency control hierarchy during this measurement:
MCL Crossover ~ 30 Hz
CARM UGF      ~ 10 kHz
IMC UGF       ~ 75 kHz
FSS UGF       ~ 200 kHz

I relied on the calibration of the IMC VCO of 268302 Hz/V, times two for the doublepass AOM.  There's also a VCO zero/pole of 40/1.6, the IMC Servo Board fast path signal coloring (Fast Option 200kHz pole, Fast HPF 70kHz/140kHz, and Fast Gain), and the FSS CLG.
The calibration looks like this:

where
 is the measured IMC OLG, and
 is the measured FSS OLG.  (This FSS measurement is a little old, things could have changed, but the gain settings are the same: 20 dB Common and 9 dB Fast gain)

I cut off the spectrum at 30 Hz because that's the MCL crossover freq and I haven't included the slow path in the model.  The low frequency stuff greatly increased my RMS, but I doubt this is really the case since the suppression of MCL is insane.

Frequency RMS from 30 Hz to 2 MHz: 1.1 mHz