Chris,
I never liked the apc16x4W on my YS91AC. The prop is so heavy, that the engine sounds like one of those old 1300 cc - 30HP VW engines. It picks up revs really slowly and takes a while to slow down. I like good throttle response when hovering and 3D-ing. I like the apc15x6, and if that's not enough, try the 15x7.
DKjens