A couple of months ago I had a discussion on the Biblical Horizons blog here. Both sides seemed to be talking past each other. I thought about it again today, and I think I can succinctly phrase my chief concern.
"It was a very bright day, for both the sun and the moon were shining."
I suppose no none would be silly enough to actually write this, but if they were, they would not communicate so much the brightness of the day, as the dimness of the sun.
Statements like (and I'm not quoting you) "God blessed Mary and Joseph with Jesus, but continued to bless them, increasing their honor with more children." makes the same mistake as the above quote. It does not so much honor Mary and childbearing, as minimize the honor which is Christ Himself.
Similarly, consider the following (rather silly) statement "Though Aristotle had many great writings, though he nearly single handedly founded the study of Rhetoric, literary criticism, metaphysics, science, astronomy, and many other disciplines; the honor in these hardly deserves mention next to his greatest honor: he was the tutor of Alexander the Great." Though this statement superficially purports to praise Aristotle, in fact, it is (rather clearly) over the top praise of Alexander the Great.
But if we change it slightly, substituting Mary for Aristotle, and Jesus for Alexander the Great, it is no longer excessive, but a fitting praise for Jesus. And Orthodox praise of Mary, in which the praise of her as ever-virgin plays a large part, has become such praise of Christ. As such, we must be very careful that in correcting errors they have made, we do not make them say something like "Aristotle is chiefly to be honored for tutoring Alexander, but aside from this he has many other great accomplishments, including the founding of the disciplines of..." which, though more fitting praise of Alexander, is nearly blasphemous when made praise of Christ.
And my concern with what you have written about Mary here, though it is in many ways admirable, is that it falls into these two traps. In the first place, while attempting to honor childbearing, it in fact dims Christ; and while attempting to correct Orthodox errors, in fact, treats Christ as just another man.