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oh..okay, thanks...can't be shown up as url, because it's not used in href or src attribute... thanks greg for your help! @all other experience are welcome

The fast answer is: No. Or, at least, there aren't actually studies, which offer correlated data about Microformats and Rankings. What Schema.org allows is a better, semantic, comprehension of the content of your pages by the Search Engines;; an higher % of CTR We may also hazard the hypothesis that Google may consider the CTR percentage an user signal valid also for ranking purposes (as, similarly, it may be the Bounce Rate percentage), but - still - we are in the fied of hypothesis. What is sure, it is that doesn't exist a direct causation between microformats and rankings. Finally, about your products being listed in Google products, again, there is not a direct causation between having your products listed in the Product vertical and organic ranking. Both are based over different algorithms, as it happens when we deal with Local Search  and classic organic results.