On the subject of image quality can only say the following. The recordings have become absolute top. However, the AF works in the border area is not one hundred percent (Good thing you have 2 hands and eyes, then does that also manuel) But that is really the only real drawback compared to the 50 1 / 1,4er Canon. (And how many times you get into this area ??) All that matters is the image afterwards!
Conclusion: The EF 1.4 / 50ii Although the slightly better lens, but the significantly higher purchase price bears no relation to it!