That sounds just like a typical YZ from way back, doesn't it? The notchiness going over neutral was one of the first things I noticed about our 250F.
yes it does. I never did grind the star wheel on the 250's as it didnt take a lot to make sure you stood on it to shift it down. I will see how these play out, and maybe see if factory performance offers one for the 450. They have them for a lot of others.