Dasher, until Norma got CIP, was a wildcat. Guys who wildcat are fucking fanatics. Once they find their personal flavor of crazy they tend to stick with it and if X doesn't fit into their box well then X is junk. That's what happened with the Norma Dasher brass. A lot of butt hurt over it not fitting in "their" chamber so they had no reason to even give it a try.
It's excellent brass, and has a long 6BR neck so you get a bit more boiler room to make up for the thicker brass. The Gen 1 brass has some thick rims, but all the gen 2 brass is excellent and should need no mods to the extractor. I have several hundred gen 1 and gen 2 and the shit shoots great with zero prep.