Thanks - You're right about frei punkt, and the very small craters, but it doesn't matter...
You and Mark right about the lack of atmosphere and frei-punkt,
BUT the ejected material still would lack the necessary velocity...
First off, ejected material has velocities nearly somewhere around an order of magnitude lower than impactors...
You're also right about the very smallest craters,
BUT there is also a size constraint on material ejected from larger impacts... thus ejecta can not produce the larger craters claimed as being "secondary"...
As for my "obsession" with cometary impact, I simply agree with Shoemaker's view on it.
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