I just completed Hats N Kats (Kats by Kelly) with RG Very Velvet for the hat and RG Fuzzy Stuff for the feathers.
Caveat: Very Velvet is very pettable, makes a hat that actually looks and feels like a felt hat. But if you are anal about getting your defining backstitches in precisely the right spot, it may not be a fiber you want to use. Those furry stitches blend right into one another without massive amounts of lighting and magnification.