After days of trying these are the best settings you will get for max smoothness min artifact.
levels.pel = 2;
levels.gpu = 0;
...
smooth.scene.limits.m2 = 7200;
smooth.scene.limits.scene = 10400;Artifact masking disabled. Svp shader 21. Frame rate conversion to screen.
This made my slow pans much smoother but also made artifacts more visible with fast motion action. I think it was always there but now I have clearly seen it, I can't unsee it. When you pause a fast action scene the screen looks like it is melting. So I've stopped using SVP.