I've only experienced on two band Simpson a couple years ago, a used T2 from the BST. The hair was different, but not for me.
I shied away from them for a long time, but have always been drawn to them and their handles, history etc.
Long story short, a 2-band Manchurian M7 will be in my hands in about a week.
Very much looking forward to it for many reasons....handle, hair etc.
That's going to be a great brush, Bruce.