This Dual ULM 66 E is an Ortofon itself. And it will approximately be equal to an old OM10 ("MkI"), I think.
IMO all models 20, 30 and 40 are better than a 66 E. Because I think a 66 E is a shank mounted ellyptical. I each case not a refined fine line nude one like OM40.
The providers sell styli which fit both OM10 and 66 E. And the OM styli are mutually compatible. So the OM40 stylus will work very well in a 66 E- body.
OM 10 is an elliptical shank mounted, standard model
OM 20 is a naked elliptical
OM 30 is a nude fine line
OM 40 is only still there as a stylus at the moment: nude elliptical fine line FG70; not as a complete cartridge.
The more refined models have more expensive parts for the tip and probably for the stylus itself too.
A fine line tip is more critical according to VTA, azymuth accuracy, etc.
The newer model OM's are OM10 Super with better magnetics in the body and an improved design for the moving parts: they have a better mass spread.
Ortofon does not tell us if the recplacement styli are real Super- Series models, but let's agree that a OM 20 replacement stylus will even outperform an OM10 Super cartridge.