You can't worry about shedding when you order a brush....it could happen with any brand, Shavemac included. If you really want a Simpsons brush, go get one! I have a few and love them.Thanks guys, this was really helpful in narrowing things down. I'll probably target a 20-22mm silvertip knot in a fan shape, with a 42-46mm loft. At least I'm in the ballpark now. I might tweak this over time if my experience with my new WD opens my eyes up to difference things, or if I just learn more about brushes in general.
Now I just have to save up... And avoid wasting that savings on a Simpson instead. They just look so damn good on paper.