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A site with a lower domain/page authority may get filtered out by Google. Why don't you use cross domain canonical tags if you can't fix the duplicate content issue at the moment. There is a good post on this topic on seomoz. You just need to search for it.

What about in the case where putting the MPN (manufacturer part number) might be advantageous? Would you have the main product page, and use many MPN's in the Title, or H1 tags, or product name? Lots of people, when searching, use "Manufacturer MPN" as their search when they're in buying mode. I could see how having separate pages for each would be useful in this case, increasing conversions & rankings because of the MPN-specific content. Love to hear your thoughts.