I had a good conversation with a Escort/Bel engineer today. And he answered many of questions and put to rest some speculation as well.
Here are some of the answers I received.
1) The variances in performance can vary from detector to detector of the same model. Because there are different suppliers for the same components from week to week. Thus a batch can vary...
There are minimum specs that these components have to meet. Its apparent that some suppliers he believes exceed the specs. Thus resulting in a "hot" unit.
2) The firmware in the STIR plus NA and the Euro version is identical. The added features reside in the module itself which has no bearing on performance. However the firmware in the receivers "waveguide antenna are the same. And that goes for the older STIR as well. So there is no detuning between the units. Which was my conspiracy. So now i can sleep at night
3) The RDR "off" ability to enhance sensitivity is known by the engineers. But i dont think he was specifically aware of its enhanced in shots under 200ms as noted by nine_c1.
There where a few other questions but that is the jist of things.