I've noticed a bit of stutter here or there on the 6s Plus. If you'd like to see for yourself, scroll through the gallery in Workflow or the home page in Pinterest. Also, the 3D Touch menus on the home screen stutter a bit when launching. 6s users: is the stutter present for you as well? I'm on 9.0.1 now, but I checked 9.1b2 as well, and it was present.