I messed up a little with getting screen grabs while getting the HallC+Cosmic rate, and didn't fully catch the number while the laser was off. But, what I have is:
Rate_A+C+Cosmic 56 kHz
Rate_C+Cosmic: 200 something Hz (less than 300 Hz)
Rate_Cosmic: 16 Hz
Using 300 Hz for Rate_C+Cosmic gives a bleedthru of 0.5%, which is ok.