I'm not one to believe a forum post as gospel. I'll buy a set from the actual factory and put them up against some second hand webers that I have. The Chinese makes are cheap but they aren't better and they aren't as well made. The casting marks are indeed a good indication of this and some of the machine work isn't as precise as a genuine weber. Generally the Chinese ones work okay.

From what I understood the equipment was moved along with the production from Italy to Spain, so I'm surprised to hear that there are complaints of the items made in Spain when the production line and process was essentially the same.

Not to cause an argument, but Chinese manufacturers, especially casting companies are renowned for cost cutting and this is directly reflected in the product. If you're prepared to accept slightly lesser quality in lieu of a lower price tag then these carburettors are for you. The champion carb is the genuine Weber, and the DCOE is certainly their flagship model. Personally I think dellorto are the very best however I will agree that the alloy used by Weber is superior, by a long margin.