Hey jnorman, thanks for the info about your testing.
Here's some data from Rycote's microphone database:
Neumann KM184AT4051aBeyerdynamic MC 930It shows the Neumann KM184 output at 15mv/Pa, the same as Avantone's spec for the CK-1. The 4051 shows 20mV, and the Beyer MC 930 clocks in at 30mV!!
For the same input/gain, this would suggest roughly equal output for CK-1 and KM184, then pretty wildly different, hotter, outputs for the other two, which doesn't seem to track with your results. I am in truth a serious noob as far as experiencing lots of different mics. Obviously the numbers don't tell the story of different mics' character and flavor, but is this also the case as far as signal output strength? I.e. maybe the test tones from which sensitivity specs are derived don't reflect the output given real world sounds and music?
In any case I am more and more encouraged about my CK-1'S

Peace,
Sanaka