TUNGSTEN by brand name is there a difference?

I've seen lots of debate out there about different types of tungsten, includind Jody's youtube clip where he actually tests the different types, and there's a thread here on different BRANDS of welding rod, But I have not heard wether there's a difference in tungsten of the same spec offered by different manufacturers. I.E., I use 2% thoriated 3/32" for almost everything, would the extra $$ for Sylvania versus the diamond ground, radnor, weldmark, or other brands be justified? I have seen first hand that the overwhelming majority of tungsten out there is coming from China, probably from the same factory. And you can observe that although the packages may be of different colors, they are otherwise identical, right down to the serrations on the label. No prob there. But does that factory sell there batches that might be at the razors edge of the spec as a cut rate label? I work primarily in the machining industry, and there you can take a 1/2 inch carbide endmill from brand x versus the same size and grind from brand y and even with the spec being the same, the difference in performance can be profound, and usually but NOT always related to price. Anyone out there in the know?