Booky,
I concede both points.
In the first, I was only speaking about the entirerly hypothetical. GS v IAS is indeed a sensible measue of the effects of windshear.
In the second, certainly true and I have done just that, but the initial misconception usually comes from people saying that momentum is speed (scalar) over the ground times weight, when velocity (vector and reference ANYTHING) times mass in in fact the case.