I am happy to let it rest. I have recently measured a few off-road courses for certification, using a cal course that is on pavement. These have been 5 and 10Ks. RRTC data seems convincing that measuring off road with a road calibration is unlikely in itself to cause a short course, more likely a slightly long course. My only question now is, how much longer a course might this tend to create, and would that difference tend to be exacerbated for longer courses?
Repeating a prior question I posed that no one answered, "How long is too long?". To this I add "Does using a cal course on pavement tend to produce excessively long measurements on non-paved surfaces? Are these answers already out here somewhere?