>>4334798>>4334917There aren't really any downsides. The Chinese are just better at this than the Japs now. It's the same in the audio community. The chinks make headphones and amplifiers that are better than Korean and European brands for 1/4th the price.
Also have a look at the 50mm f1.1 from MrDing. It costs less than $200 and is better than Leica.