The f/1.4 Nokton is a considerably older design, very compact, likely intended for film. Mine was new in Mar 2005 and probably from the second production run. The f/1.2 lens is very recent, so may benefit from optical improvements, and surely made expecting use with digital camera...
Ah, I see I made some notes about the f/1.4 Nokton:
While this lens is just fine on film cameras, it's unacceptable on the digital Leica M typ240, smearing corner resolution, and strong corner illumination fall-off and cyan color-shift... the wider the aperture the stronger it gets and the closer it moves toward center. The latter issues might be helped by coding the lens. The "plane" of focus at wider apertures is decidedly bowl-shaped, concave. The 40 Rokkor is far superior!
I have no experience with the f/1.2 Nokton.