I have to disagree on a couple of points here. First, VAN as a component of Dutch surnames is not indicative of noble status. Unlike the German VON it retains is original sense, "from" before a locative name. Second the -ov ending is common throughout Russian society, not confined to families of noble ancestry. In fact some of the highest ranking families didn't have surnames ending in -ov. Think of the Princes Kropotkin, Obolensky, Galitsin.