Hmmm...I observed the jerkiness as well, before I resized to 1280x720 or set output="flow", I think.
Here my script which I used for comparison:
Code:
clip=DGSource("C:\Temp\Selur\forInterpolation.dgi")
clip=clip.bilinearresize(1280,720)
conv1=clip.changefps(60000,1001).subtitle("ChangeFPS",x=20,y=20,size=32)
conv2=clip.framerateconverter(NewNum=60000,NewDen=1001,preset="normal",BlkSize=32,output="auto",SkipOver=25).subtitle("FrameRateConverter",x=20,y=20,size=32)
conv3=clip.interframe(cores=4, gpu=false, newnum=60000, newden=1001, tuning="film").subtitle("Interframe",x=20,y=20,size=32)
return stackhorizontal(conv2,conv3)