I redid the measurement of Schnupp asymmetry today and found it to be 3.8 cm 0.9 cm.
I measured a phase difference of 5 1 degrees between the two paths.
The uncertainty in this measurement is much more than gautam's 15956 measurement. I'm not sure yet why, but would look into it.
I used the Valera technique to measure the Schnupp asymmetry to be , see Attachment #1. The data points are points, and the zero crossing is estimated using a linear fit. I repeated the measurement 3 times for each arm to see if I get consistent results - seems like I do. Subtle effects like possible differential detuning of each arm cavity (since the measurement is done one arm at a time) are not included in the error analysis, but I think it's not controversial to say that our Schnupp asymmetry has not changed by a huge amount from past measurements. Jamie set a pretty high bar with his plot which I've tried to live up to.