Very nice and thorough description of your build experience! Keep us updated!
I'm by the way, still riding the abyss. This is my snare, doing steady 5-inch velocity strokes. As you can see the output values are all over the place from 1 to 69, but xtalk and retrigger is gone and there are tonnes of options untouched... "To infinity and beyond!"
The most important settings to get consistent velocity data are: Threshold, HighLevel and Curve. Curve is especially important since it is meant to tune relation between the hits' strength and MIDI data velocity. If the Curve is not set correctly for your particular pad, even the slightest variations in the hits' strength will lead to huge variations of the MIDI velocity.