I have insufficient knowledge to disagree with anything you've said, so I accept it as accurate. However, I think you are missing the point of focus that zedman intended to raise.
I have no problem with the idea that very little speciation occurs as a result of changes in chromosome numbers. But it seems that this particular mutation is the one that zedman wants to focus on. He begins with the assumption any change in chromosome number results in sterility. Obviously, there have been many such changes over the course of natural history. If his assumption is well-founded, it would present a serious problem, regardless of other types of mutation that may occur.
Wounded King purported to present one example where a change in chromosome number in fact did not result in sterility. (I don't mean to suggest that WK is wrong. I have not read his source so take him at his word that it's accurate.) At a minimum, it seems that this example is sufficient to overcome zedman's assumption that any change in chromosome number results in sterility, unless zedman can present evidence disputing WK's showing. Once this assumption is overcome, it seems that his objection that sterile offspring cannot produce a new species has been rendered irrelevant.
If my understanding of zedman's point is inaccurate, well, never mind.
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