Simpson has Limited Edition 2-Band and Manchurian G3's available. Occasionally they have LE's in Best. I have one.
If you're curious read up on Simpson Pure. Deserted Island Brushes right here.
I haven't tried an Eagle pure, though I am curious. My concern is Simpson tends to adjust density based on the hairs backbone... and as such I'd expect the pure is a lot less dense than the Best ones are.
Thanks. The best does look denser, but not nearly as much as I was expecting. I may have to try a G1 pure.
Best on the left, Pure on the right.