The value of rolloff depends on the input of the recorder, and there have been posts detailing the values of the standard coresound and soundpro's battery boxes, as well as the input values of various recorders (M1, JB3, etc).
Has anyone cracked open a DPA MMA6000 to figure out what DPA based the 100Hz/12db rolloff against? Also, has anyone determined what the input impedance is on the line-in of an R1?