Slippery smooth for me. Some aberrations around the edges, between contrast areas, but a worthy compromise.
Boy you are clever Dan !!
On the subject of smoothness, have you taken a look at Elite Dangerous with SDK1.3? They have managed to separate the cockpit from the external rendering using 1.3's built in ATW. It can be stammer city outside, but head panning is still silky smooth inside. I gather they have much lower level access to how things come together.
I still take my hat off to Dan for being able to retrofit VR onto FSX so well.
FSX is 10 years old this October!