"Marx's claims about class are NOT transhistorical. Marx's position is exactly like Geertz's. The history of all hitherto existing societies IS the history of class struggle but the classes are not the same,"
Yes, and I would say that, notwithstanding the quote about all hitherto existing societies, it is not really right to call the estates in feudal society classes (nor the pharoahs for that matter). Class implies a certain sponaneity of self-reproduction that you only find in capitalist societies