I'm sorry to hear that it didn't have any positive effect so far for your site. However, I cannot tell you when Google will activate rich snippets for your pages or whether there is another problem with your pages that may hinder Google to show them. From my experience I can tell you that my demo page is very low ranked by Google and consequently it doesn't show snippets in real search results so far. On the other hand, I know of plenty of other sites for which it worked pretty well.
So my advice is if the extension doesn't harm you page just wait for a bit more or check what else could negatively impact Google's activation heuristics.
BTW, GoodRelations will soon be integrated into schema.org, thus it makes no difference for Google whether the page shows GoodRelations markup or schema.org markup.
http://wiki.goodrelations-vocabulary.org/GoodRelations_and_schema.org